Dynaco ST-70 and 6ohm speakers

You should use whichever sounds better. The 4 ohm tap will have half the output impedance, or twice the damping factor of the 8 ohm tap, and will exert greater control over the woofer, which will either sound better....or worse.

The ST-70 was working with the Maggies for me(at the time) because I was using it only above 200Hz. Well- That was with a 6db/oct slope, through a Dahlquist DQLP-1. Solid State on the bottom. I used(and modded) the combo with a variety of speakers for about 16 years.

Hi, Is there a problem with trying 4ohm taps with 8 ohm speakers?

Mr G- You won't hurt anything, if that's what you're asking.