I've had good luck with the Furthrrr Generator. Tuning is a little fiddly, but not too bad. It's fairly stable once tuned.
-- farkas
Thanks for the reply. When the tuner LEDs on both sides say that they are tuned to A are both oscillators sounding identically tuned or can you hear a slight detune between them? Or is it more of a "close enough" type situation, or is it just fiddly to actually get the lights to indicate that its actually tuned to A.