NL5 said:
Is it possible to get a decent sounding 2 channel tube pre with spdif and aes output for a decent price - even if it has to be used. I would like a little eq and a comp/limiter if possible as well.
The short answer is "no".
The longer answer is that it's pretty expensive to do tubes right. I know that there is a myriad of cheap boxes with little "glowy things" inside... but the fact of the matter is that the "toobs" were put in the box for marketing purposes more than for audio purposes.
As for A/D conversion... whew... there are so many things that need to go into a serious A/D converter that to do one with a reasonable tube front end would be out of most people's budget... and then to add compression/limiting? You're asking for the moon.
The real long answer is 2/3rds of a good book... a book I have absolutely no desire to write... but a couple of years of working and reading and learning and practicing and you'll start to get more of a handle on what is, and what ain't possible.
If I may suggest a path... work with the tools you have, borrow tools you'd like to try, get a feel for the path you'd like to adopt, then form a financial plan that will allow that plan's adoption. Yeah, it's going to take a whole hell of a lot longer to get somewhere, but at least you'll have a better idea of where you'd like to go.
The one thing I would suggest you avoid like the plague is the gear 'roulette' path... the path where you buy things, outgrow them, sell them for a loss, acquire other things, outgrow them, sell them at a loss and eventually move up to hardware that fits your style and sense of aesthetic. The best way to accumulate a collection of good working tools is to acquire good gear, one piece at a time, learn it's strengths and weaknesses then slowly add other gear to fill out the areas of weakness.
Most important in all of this is to remember that gear doesn't make music, people make music... concentrate more on forming your technique as an engineer than worrying about the hardware. A recording studio is an instrument that is in many ways as if not more complex than than the instruments recorded in a studio.
You should know not only about signal flow, microphone selection and placement technique, but also how to get the instruments you're recording to sound their absolute best before you record them. Just as you can't go down to a store, buy a Steve Vai model guitar come home and play like Steve Vai... you can't go to the store buy a bunch of recording hardware and be a recording engineer over night. It's going to take years of practice until you can play the instrument with any degree of competence... so start practicing and don't be in a hurry... and in a few years you'll be closer to where you want to be.
Best of luck with it.