I am looking to improve the overall sound quality of my recordings. I have read recent threads about bit/sample rate and have a good handle on that. It seems as though my UA-101 has pretty good sound quality, but I would like to know if it is really worth spending more for a better interface.I have been looking at some Apogees and MOTU's, etc. around $1500-$2000, but don't know how much improvement that would make, is it really that much better? Also,depending on the answer to that question, would it be a decent fix to keep the UA-101 and spend money on better mics? I have a limited budget, and would like to accomplish better sound for the best price. I am mostly recording electric and acoustic guitars, and pop/rock vocals.(no screaming)!!. Cheers.

Don't get sucked in to the GAS trap, bluesguy. A whole industry has sprung up to cater to Gear Acquisition Syndrome, feeding on the widespread belief that sonic nirvana is just another purchase away. It's a tragedy that most people end up spending a great deal of money before they catch on to the scam. I speak from experience.

I cannot know what your weaknesses are in terms of overall sound quality, but I would be willing to bet that it's NOT your audio interface. Upgrading to an Apogee or RME might give you more features (more inputs and outputs) and some bragging rights, but it won't make your music sound better. If money is tight, you need to target your purchases for the best bang:buck ratio, and you need to begin your quest elsewhere.

A microphone purchase might be a good place to start. Acoustic guitars benefit greatly from a quality mic, preferably a small-diaphragm condenser such as the Shure SM81, a longtime industry standard that goes for about $350. Or the Audio-Technica AT-4041 for a little less. Others will no doubt offer other suggestions.

Vocals, of course, are the most critical but specific microphone suggestions are worthless because no mic is ideal for every voice. However, if you're primarily doing male rock/pop vocals, the good old Shure SM-57 is probably a good place to start if you don't have one already. It's a hundred bucks and very, very versatile.

Of course, a good large-diaphragm condenser is a must because it can do so much, from vocals to acoustic instruments to guitar cabinets. But a high-quality versatile LDC is going to run you about a thousand dollars. It's not a purchase to be made lightly!

But before spending anything, do some serious investigation into where your sound quality shortcomings really originate. You may find that it's not equipment at all. (I say "may" just to cushion the blow - in truth it's highly probable that gear is not what's holding you back.)

Listen to one of your acoustic guitar tracks in solo. If it doesn't sound good to your ear, what exactly is wrong with it? If it sounds thin or boxy, the most likely culprit is your room acoustics; second-most likely is your miking technique; third-most likely is the guitar itself; fourth-most likely is the microphone you're using. Way down the list are preamps and ADC.

Listen to a vocal track in solo. Does it suffer from uneven frequency response (e.g. woofiness), plosives (e.g. loud P's) or distortion? Or maybe it's just thin-sounding. These things are usually not the fault of the microphone, but rather room acoustics and microphone technique. Surrounding the area where vocals are recorded with absorptive material will do far more than a mic upgrade, and cost less.

++1 to everything Bit said, 

Hardware is hardware and to my ears the difference between entry level gear and pro might be a very small, almost unnoticeable.  

Better gear will make a difference but I would start at the front end before going that route. 

A better guitar! 
A better mike! 
A better voice ! ha ha! 

And how you layer up your tracks. I listen to a lot of songs on the song forum and most have overdone the whole process until the song is lost in the mix. 

For me adding compression as I sing has worked wonders to my vocal tracks. So I would recommend a hardware compressor before I would think of any other gear. And yes finding the perfect mike for YOUR voice takes experimentation.  

+1000 to what Bitflipper said. The most important place to start is room acoustics/treatment. You can have the greatest equipment - but if your room is not treated, you will get poor results.

Wow! this is great advice! I am a little surprised. I do have pretty good instruments (U.S. Fenders and Martin acoustic), so I think I am good there. But my Mics are pretty basic. I have a LDC but is is only an Apex 415 ( about $175). I do have a Shure SM57 that I have used for close-miking electric guitar, but honestly it doesn't seem to sound that good, it's very low/endy(is that a word)?? I don't know if I got a dud. So I'll think about an upgrade in Mics for sure. Regarding the room, I have been recording the vocals in a small (8x8) room, with bare walls.No "padding" or absorptive materials. What specifically would you suggest? Also, would the same apply to guitars? I have heard different things about that, that some rooms (bigger, more wood, etc.) are good, and others say not too much "bouncing" of sound (more carpet, etc.)Ideas? Thanks guys!

An additional question in regards to Cactus Music's suggestion of outboard Compression Hardware. Would most of these processors sound better than the compression/EQ etc. that Sonar's software offers? And if so, any suggestions on a good brand that works with Windows/Sonar? Brian.

I agree with much said.  Usually little problems get added up as you proceed on down the line, until the final results aren't so stellar.  Equipment nowadays even at entry level can be quite useful.  Typically the cheap stuff just will finally break and you get what you pay for, where as the quality gear, holds up or has subtle nuances that can be beneficial, if you know how to deal at that "subtle level".

I'm not so sure I agree with the room acoustics being a big issue as many suggest.  While I do have treated rooms myself and it was a huge improvement, it was more so for accuracy in playing back and hearing what I recorded. And yes of course, great studios have great recording rooms.  But when a mic is fairly close to the source it is recording, typically room acoustics are completely negated.  I've seen this with first hand experience in world class studios, where a guitar amp was put in some hallway for isolation, had a close mic SM57 on it and you never heard the "hallway".
I'll totally agree that when you start moving mics further away, then yes, you are capturing the total sound....room and all, but don't jump into the "cover you walls with bass traps and absorbers" syndrome, which is just as much a GAS as buying equipment.  I record much of my stuff direct and might only use a vocal mic, and room sound isn't even in the equation.  However, if you want a "natural" sound in a "wonderful" room, you need that "wonderful" room.  If you use Toontrack drums as an example, room sound is already provided in their software....and probably much better than you'll ever get at home.

The whole trick in my opinion is to learn to listen.  If it sounds bad, why?... then make adjustments until it sounds better.  If you need to single out tracks as suggested, that's one of many good ways to help determine.  There are no short cuts or special tricks or equipment that can replace good ears that can deduce WHY it sounds bad or what is sounding bad about the recordings.  The better the skills, the quicker you can get to better results.

What mixmkr is saying is very true. If you want to start doing the theory if you have your mike set-up at some point where the direct and the reverberant sound are equal then you will hear a lot of the room. But as you half the distance ie put the mic closer to the source the direct signal will increase roughly by 6 dB and the room will drop by a similar amount. Half it again and the direct signal is now 12 dB louder and the room is 12 dB quieter. Half it again eg get pretty close to the 12th fret and you are now 18 dB louder with the direct sound and 18 dB softer with the room. You will not hear the room under these conditions.

So careful mike positioning can virtually eliminate the room no matter how bad it may sound. I am sure your room is not that bad either.

Be careful getting involved with using outboard compressors as well. If you know how to set your incoming recording levels correctly you wont need them at all. You also run the risk of printing a track with poorly set compression that you cannot undo. Once recorded there are many software compressors that will do the job just as well as any hardware compressor. 

To answer your question about a vst compressor VS a hardware. 

The VST compressor is applied after the signal has passed through your audio interface, Unless you have real low round trip latency you will not be able to listen to the results. And your input could have overs as the VST is applied after all input stages, so it's too late to stop overs. 

A Hardware compressor on the other hand compresses before your interface and you can hear it's results using direct monitoring via interface headphones. 

You have to have the right combo of equipment to use a hardware compressor. A mixing board or a mike pre amp with insert loop. 
There might be compressors with mike pre amps built in. Some interfaces have insert loops. 

The results is a vocal track that is "hot" even during quieter, softer vocal parts and levels cannot go over the top if you hit it hard. I just find that my lyrics are much easier to understand if I work with the compressor before the A/d conversion.
 As I sing I watch the compression level and adjust my position on the mike as I work. 

I believe with the signal to noise ratio obtainable with digital recording nowadays, front side compression going in to be recorded, is needed much less than in days of past.  You can set recording levels redicously low in a digital recording, that you don't need the "safety" of a compressor (or more so limiter in this case), to prevent "overs" when recording.

Also, in the days of tape recording, it was more needed that one needed to record as "hot" as possible to overcome the inherent sound of tape hiss, and therefore easy to accidentily overload a recording into unwanted clipping or distortion.  Additionally, unlike software plugins, you may have had a limited number of hardware pieces to use at one time, and therefore used them (and also made final decisions), during the tracking.  Potentially that same hardware compressor was then needed again on that track to smooth even more or to be used somewhere else, getting the most number of uses out of one single piece of gear.  Plugins quantities are typically just limited in number by your computer's power.

As mentioned, you are now making FINAL decisions ...which actually is just fine... about your recordings.  However like reverbs, etc... if you don't like the recorded compression you just did, it is very hard, if not impossible to correct or remove it.

All that said, Catus has found a route that works for him, and that's one of the solutions.  You're just being cautioned that recording dynamic effects typically is permanent and can just as easily be added later.

Then there is the topic of making ALL decisions at the end, and overlooking the importance of doing it right, right from the start.