BenMMusTech
 
That's how I work these days, the screen never lies in that regard.  I can see from that screen shot that there is a nasty bump at around 70ish Hz, and one that could be tackled in a couple of ways, either use a low-cut filter and do a general clean or maybe just a shelving filter and gently massage it out, actually there are four ways, or a general EQ and carve it out or finally a multi-band compressor.  But if you are in the mixing stage and about to go into the mastering stage...the question is what is causing this issue?  The mix from that screen shot is not very even.
 
Ben 

But considering that you don't make records to make music anymore, you might as well do things your way, take the time, and make it more of a personal, artistic statement.

Danny Danzi

Rain

MakeShift
I think you hire a Mastering Engineer depending on the quality of the end product you are expecting to obtain.  If you are a professional musician wanting to put out polished professional work, you hire people like Danny and Jeff that have REAL skins on the wall.  You would probably do best to track in a true studio environment as well.....with real instruments.  If your a home studio artist posting 256 mp3 files, you can do fine small mastering your own. 
 
I feel very confident that if either Danny or Jeff were to Master a project that I did, it would turn out far better than what I could do myself, even though I have been doing this for 10 years as well.  It's called experience, quality equipment and tested environment.  There is a reason that clientele still go to the proven, for the professional end product.     

Ever since I've started working on this project a few years ago, it was clear in my mind that if we were to release anything, I'd at least consult Danny, possibly have him work some of his magic. But at least hire him for a bit of input.
 
But that depends on what happens with the project. Me, I'm all for the home made, independent  album, but I can see how my wife could wish to bring it up a few levels, go to bigger studios, and all.
 
But considering that you don't make records to make music anymore, you might as well do things your way, take the time, and make it more of a personal, artistic statement. 

I think you guys are both spot on here and are thinking the right way. I also think Ben went a bit over-board on what he thinks about this and has lost the significance. Let's totally remove the term "mastering engineer" for a second. Though I still think it's a necessity in certain situations, what you guys said above nails it perfectly. That said...there are important things to consider that I'd like to reiterate.
 
1. The extra set of ears from someone you trust is immensely important. More so than any mastering engineer, that person that can hear two gnats getting it on in the other room is worth his/her weight in gold if you are serious about your music. Even if you're just doing digital downloads.
 
2. I can't stress this enough. You recorded the music, you mixed it and listened to it far too many times and have lived with it too much to be subjective the right way. If you are using one set of monitors, you have the possibility to cloud your judgment further. Your judgement will never be where it should be...and I didn't have to go to school and get a degree to tell you that.
 
If this is for your head, it's fine to do whatever you want. If it's for sale, don't do what everyone else is doing to degrade music. Send it to someone. Heck try me first, I won't even take your money if I can't help you and I'll give you advice on how to mix the thing better if needed before we even master it as part of the package. That's not meant to be a shameless plug...it's meant to be truthful and tell it like it is.
 
3. Mastering is still needed. Whether you are going to vinyl or not, it's nice to level things and work up an eq curve that works for your mix as well as your entire album. It's really nice when you have someone doing this that knows what they are doing. Not all songs need extensive mastering. Most times when the mix is right, a little polish is all that needs to be done. The question is, can you really make the right call to do that without over-doing it? Most can't.
 
4. Relying on analyzers: You already lost if you watch these things too closely. I totally disagree with anyone living by this way of thinking. Don't fall into this trap and don't listen to anyone that tells you to....regardless of what degree they have.
 
I've mixed and mastered so many albums, I'd be curious as to how many I've actually done. Does that make me an expert? No...it makes me a dude that mixed and mastered a lot of albums. LOL! What I HAVE found out in doing so many is that there are times when your analyzers give you incredible stats where the song does not sound good....and there are times when you have a crappy looking analyzer yet the song sounds good. Don't EVER take a look at something and assume that little bump you see is a problem.
 
That little bump may happen one time in the song. Resetting your meters and watching them closely REALLY tells the story. This is one of the greatest things in Sonar's wave form preview. You can see a peak being created in real time so you know where it is. Ben was quick to jump on that bump he saw, Rain...without even hearing it. A HUGE mistake if you just cut it.
 
You listen to the music and believe what your ears and monitors are telling you. If you hear a problem, this is when you turn to your analyzer for a bit of help. Even there, they are not the be all end all of sorting out your problems. One little "whoomf" from a high gain guitar chug that may not be high passed enough and it will throw 120 Hz through the roof....you see this on the analyzer and curb 120 Hz. That's not only the wrong move, it's absolutely ludicrous.
 
We have another thread going on about controlling peaks. This right here counts as a frequency peak, which is different than a transient peak. Having an analyzer jump high one time showing you an off-set curve is nothing to be alarmed about. How does it sound? Is the bump you get making the material sound bad in that spot? These are the things to question.
 
I can go on and on here and then argue with Ben, pistol pete and anyone else that feels the need to take a shot at me. I really don't care to do that and am perfectly happy with who I am, what I do, as well as how my material sounds at the end of the day. My clients are happy too and I thank God every night for the business that comes my way.
 
At the end of the day, you guys should do whatever makes sense to you...but always look into the sources that you listen to. If a person can't lead by example in this field, 7 times out of 10 they just become a windbag of useless jargon while polluting the minds of those who are really in search of knowledge. This field is difficult enough as is without those types ruining it for the rest of us. Choose wisely. :)
 
-Danny

batsbrew
 
RAIN,
you might want to investigate Sony Acid.
 
i used to have it,
and created some killer drum grooves very quickly with it.