I would like to try a 07x or a higher end tube preamp for a bit more warmth, but I’m also considering a change to less bright speakers instead to get the same effect while maintaining the crystal clear transparency of the LA4.
I had the LA4 and 07x on the same system to the CODA #8 and it was the best of both worlds. Sometimes when that bit of extra warmth is needed I switched to the 07x. I tended to like hard rock with the LA4. Both are good with all music, it was just a matter of preference on a particular day.
My LA4 is now on an all-Benchmark system in the Living room. Which sounds different from the CODA/KRELL system in the office.
BTW - the $600 Topping pre90 sounds like the LA4 on my Benchmark AHB2 amps. Though on other amps I had issues.