Dying Bassman 100

[bzzztraffe]

I recently did some upgrading to a Bassman 100 head & it sounded fantastic!
I was thinking about changing that silly bias balance to a true bias adjustment control, but had a gig coming up so put it back together for a later fix.
I fired it up today & stupidly forgot to reinstall the power tubes.....no sound....duh!
I powered it back down & put the 6L6 tubes back in, let it warm up, took it out of standby & now it sounds like it's fighting to get sound out unless I turn it all the way up.
What kind of damage could I possibly have done by leaving the power tubes out earlier?

[phantomman]

Theoretically, none.

Some servicing checks are performed with the power tubes removed -- no harm should occur during these tests. It's possible one or more of your 6L6's has finally given up the ghost. That's the first thing I would check.

[Hiwatt]

I recently did some upgrading to a Bassman 100 head & it sounded fantastic!
I was thinking about changing that silly bias balance to a true bias adjustment control, but had a gig coming up so put it back together for a later fix.
I fired it up today & stupidly forgot to reinstall the power tubes.....no sound....duh!
I powered it back down & put the 6L6 tubes back in, let it warm up, took it out of standby & now it sounds like it's fighting to get sound out unless I turn it all the way up.
What kind of damage could I possibly have done by leaving the power tubes out earlier?

I wouldn't have thought you would have caused any damage powering up the amp with the power tubes removed.As long as you had the speaker connected?