i have not heard the profire 2626 but i used to have an m-audio octaine wich looks like the pre's on the profire were taken from that. i recently bought a onyx 1200f and i can only give you my opinion that the onyx pre's are much nicer to me than the octain pre's. they have actually exeeded my expectations. it's the first time that i've been 100% happy with an interface, although to be fair, the octaine was not an interface.
Having gotten my Onyx 400f at around the same time my friend bought his ProFire 2626, we did a for-fun session where we recorded drums and some guitars on both units.
Since there are several components at work at in each interface, I can't comment directly on the preamps. To my ears, however, everything about the Onyx 400f was more euphonic: the drums, in particular, had more depth and produced a more 3D-realistic image. This was even apparent at the time of tracking.
The only "good" preamps I own are a Groove Tubes The Brick and a Summit 2BA-221, so my bases for comparison are limited. Even still, some instruments -- kick drum in particular -- are inextricably paired with the Onyx over my pricier pres.
This post is quite so I am answering this question as flexible advice for anyone who may have similar questions.
Profire Preamps vs. Onyx,
I have used both the Profire and Onyx and think that your question may be answered better if considered differently.
Let’s assume that you really want to get the best sound for the best price and if at all possible the least headache and obviously the best result.
Also it is important to consider if you are recording for money (subcategorized by recording for money as an engineer or musician or both).
I may be able to safely assume that you aren’t in a band since you didn’t post a myspace page or some other reference to your music studio so you likely don’t have recording studio either.
Again these are merely inferences but also good to think about... If you do have a band we’d like to hear you results with what you have and whatever you chose after asking questions on this forum.
I could begin by suggesting that since the profire is a wonderful option since it sounds great and is a lower price that you should strongly consider it, especially if you are worried about preamps you should really consider acquiring dedicated preamps. But since you don’t appear to be in the business or are probably new to it this may be overkill and/or out of budget. However if you are new It would be best to add time effort and history, some experience to see if you are still dedicated to the recording process as time goes by or rather to see if you are just excited about music performance and don’t really go to much into the recording aspects.
All that aside if you have the budget and/or are willing to sell your gear should you not pursue the craft by all means upgrade to the best stuff you can. However if you have the money to get the Onyx you may want to consider spending just a few hundred more and purchasing the Apogee Ensemble. Out of all three of these I think this one was the most seriously dedicated to pristine sound and lasting quality.
Like all other things that are part of the Kosmos we are evolving along with the Kosmos itself. Yes we make habits and find a groove or comfort in the the repetitions we create as well but the point here is you are attempting to find something new, different, better.
If you are looking for the best sound take into consideration your existing computer or whatever computer you’ll be using your interface with. What can it handle? will your interface assist your computer, adding to its processing power or will won’t it?
What kind of reference will you be using, monitors, headphones (multiples, variety)? Is this at home will you be able to play music loudly without angering or offending others around you? Will you be sharing it with others do you trust them not to break it or buy it if they do break it. Do you have a plan?
In the end this really comes down to a question of your ears and your willingness to find your strengths and your weaknesses. Maybe you are quite a capable engineer for a small group of techniques so if you want to specialize then get the interface that helps you enhance your specialization but if you only specialize you may run the risk of becoming overly limited. I suggest going with your long term or non instantaneous gut feeling. In other words what ever interface moves your mind’s or ears gears over an appropriate period of time to decide (go with or work with). Because being excited about your purchase will motivate you to use it and using it, is what will allow you to develop the skills and ears that will help you with tough gear purchasing decisions later. Even if you end up making a bad purchase you make the best of it and learn how to work around or though the problems you encounter creatively. This quality, or state, or attitude of creativity is far more valuable than any preamps you can buy.