Marko wrote:

I was told that metal film resistors should not be used with tubes because
they make the circuit ring. Carbon films sound better.

I see no basis for this in specifications for metal films. Any opinions or
facts?

Facts? There's no problem using metal film resistors in tube gear. But
you should use 0.5W types, as the 0.25W types often have a low voltage
rating.

If they sound better or worse than carbon films or carbon comps is a
different matter - try all types and see what you like.

I just use what I have. Mostly metal films and sometimes ancient carbon
comps.

Best regards,

Mikkel C. Simonsen