There are many SET amplifiers, many are excellent. You really can't compare to Lamm to a 1.25 watt Thomas Mayer 46 driving Pnoe AER BD4/5 just as you cannot compare it to a 2w 45 amp. I am not interested in comparing Lamm there. And these amps will not drive some of the speakers Lamm drives. I have heard Bionors with all Lamm and with all Kondo G1000-G10-Kagura, and prefer the Kondo system. I have compared Lamm preamp and Kondo M1000, and preferred the M1000. And I am not a Kondo fan either, they are very good in certain ways with the right speaker. Lamm is mostly an US product, and EU is way richer in SETs. Everywhere I look these days, there is a SET. And tons and tons of variety. 45, 46, 2a3, 211, 845, GM70, Eimac, many other tubes, and even on same tube many amps with different flavors.
Your question about bass quality does not even make sense to me. If something was lacking in bass, I understand, once you establish it is not due to mismatch of the amp and the speaker, a mistake often made while auditioning SETs. But then I don't select something just because it has bass. It has to play the entire gamut of the orchestra. There is flow, texture, attack, decay, balance across the spectrum including the bass, transparency to recordings keeping the realism, many things I look for.
If you wanted bass on some of the cones, which some of the Lamm owners tend to have, find yourself an Eimac amp. Trafomatic, NAT, KR, all have good bass at various levels, plus drive and dynamics. All sound different.
Right now I am interested in finding alternatives to the Thomas Mayer 46 on the Pnoe. Because I liked the TM 46 sonically, so I would like to hear what can be better. I am interested in finding, for my own personal use in the future, something that works well with Altec 817 or something like Leif's dual FLH, because these are the best systems I have heard. I am interested to find ideal amps for hORNs Universum, and maybe the Lamm ML2 can be used for some compares there, as it has a bit more grip and drive that the Universums require compared to many other SETs, KR being the other contender in the grip/drive category . And then comparing the Eimac monsters can always be fun. I have heard trafomatic on Cessaros compared to Alienos which were some type of OTLs.
There are just too many high quality options. Find a good SET match for a speaker you like and go town on it