I have to second the notion of using the available funds to fix or supplement the AC. I had the same issue in my office where I have my headphone rig. I have several tube amps there which all give off quite a bit of heat. I would have never even considered switching to SS or something of the sort, but that's just me. In your case, I feel like you heat problem will remain even if you change amps. If you notice any difference, it likely won't be enough.
In my case, it turns out the main return was undersized for the house. I guess they didn't do the best job at calculating those 20 years ago. I added an additional small return outside my office door which is in the opposite end of the house from the main return. I also added a larger dedicated run to my office off the main duct and installed a bigger vent. If this hadn't worked, my next move was mini-split.
On the other hand, a new amp to switch things up for a few months out of the year sounds like fun too. Best of luck with whichever path you take!
