Maybe Leaving SET for Solid State because I want bass

Tough question. The main problem with bass with tube amps, push/pull and especially SET is their high output impedance. Low output impedance helps control woofers. And the problem with output impedance is the output transformer. The tube amps I know that had relatively low output impedance(3 to 4 times lower than most tube amps) were made a couple of decades ago by a company called Melos. I saw the Stereophile unpublished bass response into a simulated speaker and it was almost undistinguishable from a solid state amp.

Other plusses for the amps are high power. The stereo amps are conservatively rated at 200 watts Triode and the monoblocks 400 watts. They are rich class AB. The monoblocks were25 watts class A before going into AB so your speakers would be class A almost all the time. The problems would be working on them. They are old. Schematics don't exist although a good tech can follow the circuit. Almost unknown now they should be cheap meaning you can put money into restoration. I also recall an SET Melos rated at 70 watts but I suspect they are super rare

This is just a thought by the way with some risk but with possible exceptional results.

Viva Audio out of Italy makes fantastic SET gear and has a lot of low end punch. I have heard the Viva Solista Integrated and the Viva Solista Stereo   Most recently it was the Viva Solista stereo at the Capitol Audiofest 2025 

https://stereonet.com/reviews/viva-audio-solista-mkiii-integrated-amplifier-review?fbclid=IwZnRzaAPrXzJleHRuA2FlbQIxMQBzcnRjBmFwcF9pZAo2NjI4NTY4Mzc5AAEepWyLWNYAS3Jm2D0ia62j6B4iRr4D-7fV8okUMGr3IKaJc9lPrjcbXISql8g_aem__I-Gic_jNbYVMyVSbWmSPA

https://positive-feedback.com/show-reports/capital-audiofest-2025-2/12/?fbclid=IwZnRzaAPrX3xleHRuA2FlbQIxMQBzcnRjBmFwcF9pZAo2NjI4NTY4Mzc5AAEekqBoMvFprfooMvsW1SEnFyZCIY4o5kqSQDntwf85FS6ZoleT_oHCuNt0dfE_aem_xFyuGHkJ5K3G1GyWhTLO0Q

https://www.enjoythemusic.com/Capital_Audiofest_2025/Becker/CAF_2025_Show_Report_Part_2/page5.htm?fbclid=IwZnRzaAPrX6BleHRuA2FlbQIxMQBzcnRjBmFwcF9pZAo2NjI4NTY4Mzc5AAEetbpyV4RCFKA0SVSM544w4ftXQYbRC1StKA3H1ghP32ORHkEAXX9YORbLSbU_aem_tTfwQhmXYGFEjukRyA3yxw

Interesting discussion, especially concerning SET circuit design. I will only add that in my experience: (1) solid state will offer better lows (and highs) than a comparable tube amp, but, and it is a big but, your recordings will not sound the same. Jimi Hendricks and Stevie Ray Vaughan do not sound the same with solid state amplification; it is as if they are playing different instruments.

(2) Integating subwoofers into a stereo system is a non-trivial task. Several persons have given good advice on resolving this dilemma, but much like room acoustics, there is not one solution which fits all cases, just various methods and means to achieve a common goal, in my opinion. 

Get a Krell power amp. You'll have all the bass your ears desire. Get a REL sub for perfectly integrated low frequencies.

When an individual is on the fence, a flimsy reed in their planning a strategy, it is usually due to not having created experiences for them to form their own evaluations and direction forward based on the influences of the experiences had.

The OP is a Gon Member for best part of 14 years but is not too experienced, they are a Member who makes a large amount of inquiries, looking for feedback from others. This is not a Bad Thing, but it does leave a dependency on others.

Certain Types who linger in the depths as well as similar types who are a more self promoting type will be unable to hold off to inquiries, this is Sales Prey at its best.

 What Sells On With Ease  

For the OP I suggest if a change of equipment is seen as the only option and it is ti be purchased on Word of Mouth only, not as a result of being impressed from a experience had. I strongly suggest the way forward is the one that is least costly when the outcome is a failure to ones needs and can't be lived with.

Sub's with built in Plate Amp's which are with a range of adjustments are very popular as a sale Item, both in the used and new market.

A Plate Amp' Sub per channel has the capability to create a wonderful interface for the Bass to a already in use Speaker.

A used item sale Plate Amp' Bass unit has two markets of interest be Home AV and Home Two Channel Audio, the experience can be had and the equipment sold on for as good as the purchase price, resulting in a nominal outlay to generate a new experience for the Bass in the system.

Also don't overlook that when the Bass area is better understood a very very high quality Bass Subwoofer can be built for close to $1100ish per single unit. Such a end product will not have much competition if built correctly, think $10K - $15K and upwards is the cost of the product that might show it competition.  

http://www.troelsgravesen.dk/26W-4558T00.htm

Not much has sold from Troels Graveson designs when built by a adept enthusiast for very little less than the BOM of the build. In general it is safe to say that time invested is the only unremunerated quantity when Troels Models are being experienced. This is almost a zero cost to experience, if chose to be sold on at a reasonable time line after the final production. 

Other Options already in front of you through the Thread recommendations, are a risk of a substantial depreciation being incurred and the cost of the new experience is coming at a premium rate, if now wanted to be lived with.