@wavendon - As has already been stated, replacing your pre-amp and amp with a quality integrated amp would likely pay immediate dividends. As also stated, a low(ish) powered tube integrated should have enough power with your Omega speakers, in an office system, listening to jazz at low volumes. Lastly, with a budget of $2500 you should be able to pull this off, no problem.
A couple of questions that might help folks make specific recommendations:
1. Do you have a preference for tube vs. solid state? There are arguments for either.
2. Do you require remote control?
3. Do you have any location/space considerations?
4. Will you ever have a need for a built-in phono pre-amp, i.e. do you plan on ever adding a turntable for playing vinyl?
5. Lastly, do you want to go all-in on your $2500 budget, or would you prefer to try something less expensive, then re-sell it if it doesn’t float-your-boat and try something else?
IMHO, you could get something for less than $1000 that will better what you’re using now. I believe a Rega io or the new Rega Brio would suffice. And I’m fairly certain a Croft integrated would sound great, but no remote, plus dual-mono volume control knobs. So, there are options depending on what you want/need.
Good Luck! I hope you find something that makes your system sing!