I've been writing music on my computer for quite a long time now, but I've only ever worked with MIDI/samples/virtual instruments. I live in an apartment that has a strict no instruments rule so I don't see myself upgrading my system to allow for recording live instruments via microphone or direct input any time soon.

My question is this: if I'm only using my external audio interface as a kind of soundcard to replace the stock one that's in my laptop, does it really make any difference which one I use? I have a PreSonus AUDIOBOX USB. It's nothing fancy, but I've never had any problems with it and I've always been able to get the sound that I want (so far as I am capable of with my mixing/mastering abilities).

Working the way I do, without ever recording live instruments, is there any good reason to upgrade to a more expensive, higher end audio interface? Would there be any benefit to the potential overall quality of my tracks if I had a higher end interface? 

Thanks for your help!

Quality wise? No. Thing is, even cheap audio interfaces are exceeding human hearing these days, and generally exceeding other components. Your speakers/room/headphones are going to be a much bigger issue than any soundcard. The only reason to want a better soundcard would be if it offered you something technically useful, like lower latency or additional features you don't have.
 
However the one thing to check on if you are using headphones, as I imagine you are living in an apartment is Japan, is to make sure the card has a headphone amp suitable to your phones. If not, getting a headphone amp could be worthwhile. Most pro audio card have pretty decent amps for high impedance phones, but not so good for low impedance. So if your headphones are under, say, 150 ohms, you might want to look in to an amp.

If you are happy with the end result, no need to change.  A lot of the better quality of the sound would be lost if you can't listen at loud, reasonable levels.  And as Sycraft says, a better headphone amp for your headphones if more important than raw conversion power if you are using headphones.  Some interfaces will have better latency, but that doesn't seem to be a problem for you, either.
 
Unless you just want to spend money, the answer is no.  If you do have money to burn, the Tascam uh-7000 is great w/o breaking the bank.  Superior conversion and preamps, good headphone amp, usable latency.  For the money, it is one of the best interface deals around.  I could hear the difference between it and my TC Konnekt 48, which is on par w/ RME hardware, which is very good.
 
@

Remember that exclusively using Virtual Instruments, the quality of the conversion/interface has NO IMPACT AT ALL on the sound on your printed files! The DA converter is not used when exporting to a stereo file, it all happens in your CPU.

The sound quality of your interface will only ever affect your monitoring, so having sublime DA can (in theory) compel you to make better mixing decisions.
 
Sven

I had an entry level interface that was USB and as my needs grew (more tracks in DAW, recording good vocals etc) I found the interface didn't hold up.
 
major problem I found was latency and DSP recording on vocals.  Also as I threw more USB devices onto the system the interface wasn't doing as well.
 
a better interface can help in regard to those things.
 
I went to a higher end Firewire interface that is the only Firewire device on my system.  The new interface had better preamps for when I recorded vocals.
 
if your interface is working for you there is not need for a more expensive interface.  if it ain't broke, don't fix it.  If your running into issue with your current one then address those needs and you may want a newer better interface.

First I'll agree that the Tascam uh 7000 is a great interface but it is the opposite of his needs, He just said - doesn't input audio- so why spend money on great pre amps ??  
As a few have said your choice would be to go for better drivers so you can run more VST instruments. But I think Presonus is up there among the better USB interfaces when it comes to drivers. 
http://forum.dawbench.com...mance-Data-Base/page13
 
With the same computer system, changing from a Tascam us1641 to a Focusrite 6i6 made a huge improvement for me.  And only because Focusrite has way better drivers than Tascam. Now this might change with Tascam as they just announced they will be working in house on the drivers so stay tuned. 
Latency and DAW performance is all about good drivers. I would guess your fine where you are. 

Thanks for all the input, everyone. You definitely answered my question. Until/Unless I plan on recording audio, I think I'll invest my money in a better set of headphones and/or headphone amps if necessary. As I mentioned above, and as Sycraft guessed, since I'm living in an apartment in Japan I have no choice but to mix through headphones. I do have a pair of monitor speakers that I can use to test at low levels during the daytime, but I'm stuck with mixing through headphones 99% of the time. I have a pair of Audio-Technica ATH-M50 which have been awesome, especially considering how inexpensive they were. But I'd like to upgrade to a pair of nice (maybe $500 range or so) open back monitor headphones in the near future. Maybe a Christmas present for myself :)

Thanks again for all the advice and information!

The quality of the Tascam DA is also above par.  Don't discount that!  But the bestest part, the preamps, are wasted w/ no acoustic input.  But the package is cheap enough.

skitch_84
Thanks for all the input, everyone. You definitely answered my question. Until/Unless I plan on recording audio, I think I'll invest my money in a better set of headphones and/or headphone amps if necessary. As I mentioned above, and as Sycraft guessed, since I'm living in an apartment in Japan I have no choice but to mix through headphones. I do have a pair of monitor speakers that I can use to test at low levels during the daytime, but I'm stuck with mixing through headphones 99% of the time. I have a pair of Audio-Technica ATH-M50 which have been awesome, especially considering how inexpensive they were. But I'd like to upgrade to a pair of nice (maybe $500 range or so) open back monitor headphones in the near future. Maybe a Christmas present for myself :)

Thanks again for all the advice and information!

skitch_84
Thanks for all the input, everyone. You definitely answered my question. Until/Unless I plan on recording audio, I think I'll invest my money in a better set of headphones and/or headphone amps if necessary. As I mentioned above, and as Sycraft guessed, since I'm living in an apartment in Japan I have no choice but to mix through headphones. I do have a pair of monitor speakers that I can use to test at low levels during the daytime, but I'm stuck with mixing through headphones 99% of the time. I have a pair of Audio-Technica ATH-M50 which have been awesome, especially considering how inexpensive they were. But I'd like to upgrade to a pair of nice (maybe $500 range or so) open back monitor headphones in the near future. Maybe a Christmas present for myself :)

Thanks again for all the advice and information!

The Focusrite VRM box is a pretty cool unit if you have to mix with headphones. It works well with ATH-M50's but I prefer my BeyerDynamic DT770 Pro cans.
 
Rocky

CONSIDER ULTRASONES.
 
http://www.ultrasone-headphones.com/en/