@markf31
Not sure if you are aware, it’s a common practice to run a tube preamp in front of the PASS / Firstwatt amplifiers. If you’ve not seen or tried it, look up Korg NuTube on the firstwatt site
http://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdfA few reviewers and owners of FW and DIY amps also demoing these flat tube preamps past few years. When I was doing research on the early version ".8" Pass amps a few years ago, was quite surprised to learn from Nelson directly how many owners were already using my own Cary 6SN7 tube based preamp in front of Pass SS amps. He shared he has a
"lot of customers using my same tube preamp with his amps". If you are truly looking for suggestions...
Your RP-600M and former RP160M predecessor speakers still tend to be a little bright and forward with the TracTrix. A few buddies with them use tube DACs and tube preamps in second systems, and softer input driver tubes. Folks are doing recent crossover updates on them now to help tame the RP-600Ms some more. A nice tube preamp in front of your Aleph SS amp can truly be an enjoyable way to go, fwiw.
Or, the AVA Vision SLR preamp you are considering has the switch:
- "High Filter - to tame excess brightness from low quality sources".
Best of luck on the preamp research and purchase.