parafeed amp with Hammond 119DA transformers, what is my best circuit option?

Hello,

I have worked recently on a power hungry OTL amp and I can say now I got it straight, I enjoy the sound of it and it is well above anything solid state I've tested so far.
The problem is, it is 20kg+ and sensitive to mains Voltage swing (naturally).

A few days ago I just hooked a pair of Hammond 119DA transformers on the output and I have to say I was really surprised. I expected that it will "soften" up and "wash", it did not happen at all. In fact the base got a little tighter.

Now I'm thinking to make a less power and iron hungry amp with these transformers for my 120-300 Ohm sennheisers.

What circuit options would you suggest?

Thanks!
JG