Maybe Leaving SET for Solid State because I want bass

@mdalton As best I can make out the Ayon is no different in this regard, as the bandwidth has nothing to do with the power tube (other than lower power tubes tend to have smaller output transformers which can have wider bandwidth). 

I took a look at the article at the link you provided. 

They spec the amp to 8Hz but as best I can make out, that is not at full power. I've found no tests online to show which show its full power bandwidth. It would be quite interesting to find out at what power level and frequency the very low distortion spec mentioned in the article was measured. I did not find a distortion spec on their website. 

Since there is no mention of 'parafeed' or parallel feed on their site, my surmise is this amp uses a gapped output transformer. 

The transformer cans are round. That suggests toroidal transformers in use; the website says indeed the power transformers are toroidal. Toroidal output transformers saturate very easily with any DC that the only way to use them properly is with a parallel feed circuit. The round cans might also be cosmetic; there is no mention of toroids being used as output transformers. 

BTW there is an error on their website. It mentions in several placed a tube regulated power supply, but I'm pretty sure what they meant to say there was 'tube rectified power supply' since a 5U4 is a rectifier and not a regulator tube.  

@atmasphere 

Really interesting and helpful.  I’ve been tempted myself to go the SET route with even more efficient speakers than what I currently have, so my interest here is not merely prurient.  So when you say one should prevent bass getting in, I have a couple follow-up questions:  What level (hz) do you define bass?  And if a speaker is only rated down to Xhz, does that in effect mean that no (or little) bass below X hz will make its way to the SET?  In other words, do you need a crossover or filter to achieve the objective of limiting bass getting to the SET, or can the design parameters of the speaker itself (e.g., full range driver with no energy below 50 hz, supplemented by powered bass, so that SET only driving full range driver)?

@mdalton The minimum frequency varies depending on the output transformer of the individual amp.

I repaired an SET recently that made 12 Watts. When I tested power bandwidth, I found that it hit a wall at 90Hz. Below that its maximum output power without excess distortion dropped; at 20Hz it could only make 1 Watt.

The bigger the output transformer relative to the output power, the lower it likely can go. Lundhal is known for making some excellent output transformers but even their best is unable to allow a 300b to make full power at 40Hz- its down a few watts.

So I'm saying you should measure it to find out. But in general if you cut off at about 80Hz (and use a subwoofer) you'll hear a marked improvement in the sound of any SET (that isn't a parafeed) - more relaxed, greater authority and detail. All that is needed to do that is a capacitor in series with the input that is the right value. Such a part would not be expensive at all since it does not have to handle any Voltage. 

Pick up a used Coda 8 amplifier. Good amount of Class A power and lots of current to produce fast and articulate bass. 

Coda Technologies S5.5 Class A amplifier is what I meant to copy and paste.

As stated previously, whilst not owning one, well respected listeners I’ve interacted with love it.  Good hunting.