new pre/pro recommendation request

I run digital sources (iTunes through airport and CDs on an Oppo DVD player) into an older Rotel RSP985 pre/pro feeding a Rotel RB980BX 2 channel amp. I use toslink and digital coax so the rotel does the D/A conversion.

My thinking has been to build a decent quality system using older pre owned gear, but utilizing digital sources. My speakers are GR Research AV3s but I'm about to upgrade to GR Research Neo2x speakers. I have a 12" powered sub and run everything in 2.1. I generally like how it sounds, but always wonder if I can improve the sound for little extra investment.

In the spirit of the grass always being greener, if you had $300 - $500 for pre owned equipment, would you:

1) buy a chinese tube DAC 9 (such as the Maverick or Grant Fidelity)
2) sell the rotel pre/pro for a higher end old pre/pro (like the Arcam AV9)
3) Sell the Rotel separates and get an older technology receiver (Arcam AVR300, Anthem, Emotiva, NAD or Integra etc.)
4) Some other option.
5) Come on son, keep your gear that is functioning just fine!

I'd appreciate any opinions.
I still use a Proceed AVP for movies (5.1) and its not bad for music either.. These were $4K when I purchased it and now you can get them for less than $1K. I still have yet to hear a more musical processor and I've heard a few.. Try Audiogon or ebay.
I think your should consider replacing the pre/pro with a 2-chnnel preamp and a DAC. To do this on your budget, I would purchase the DAC 1st, and circumvent the digital processing in the pre/pro, using it as a pre only. One option, the Music Fidelity V-DAC II, often show up on AG or Ebay for ~$150, and has USB and Coax input.  This leaves ~$350 for the preamp. A used Rotel or NAD can be found in this range.

Another option might be to replace both your Pre/pro and amplifier with an integrated amp. I have an NAD 526BEE which I like. New retail is $550. Sometimes these come up for sale, also the predecessor the 525BEE which is very similar and yet not to old a vintage, and would be less expensive.

Thanks very much for the responses - somehow I didn't see the a'gon notifications, so I apologize for the delay in my response. I ended up buying a used Arcam AVR350 receiver and will be receiving a GF Tube Dac this week to use for streaming music. The Rotel separates were really good, but the Arcam brings a midrange clarity that I really like. Long term, I'll either keep the tube DAC or just use the built in Arcam DACs (wolfson, I believe) and I may end up trying some tube power amps with the arcam for preamp duties only.