Too much voltage in a preamp??

Matching IS important! My friend loaned me a Morrison ELAD (small mfg. in Canada) SS preamp which I connected to my VT-100 Mk III (tubes). For whatever reason, my tubes started glowing bright blue (not good) and the sound was quite "hummy". It works (and sounds) great with his SS amps, however...

A guess. If the Lamm has a highly sensitive input, say on the order of .5 to 1 volt, the ARC probably has a high enuf output to render the volume control near useless - that is, it is way too loud when the volume control isn't even advanced to 8 o'clock when you are using sources with high output, which causes you to loose the use of the finer gradiations on the volume control. Many ARC amps either employ a built in switch to attenuate incoming signals (my SP10 does) or allows for a minor change on the circuit board to obtain the same effect. Check with ARC to see if they have a provision for attenuation.