[fidgeraldo]

I saw the specification as 50ohms minimum for TA-66. Cannot remember where.

That's even better. I saw a review of TA-66 from Reviews By WaveTheory today, and he mentioned 80 ohms as the lowest.
He said really good things about TA-66.
I will try Fostex T50rp50th (50ohm) with the TA-26S; Fostex T50RP50th are really power-hungry.

 

[fidgeraldo]

Fostex T50RP 50th is not good with TA-26S; there is a lot of distortion.

I listened before TA-26S got warm, but I doubt it would be much better after it gets warm.

 

[fidgeraldo]

I was wondering...how long is it okay to keep a tube amp on running?
Is there a limit to be sure it won't degrade the amp or tubes?
4-6-8-10 hours?

Cheers!