If you have the 135 watt Quad it is 4 ohms out. It would have 4 speakers at 16 ohms in parallel. It should also have a line out jack.
I just checked the 100 watt model schematic and it is also 4 ohm output. It does not have the line out jack. From the schematic of the 135 watt model it appears all they did was go from center tap of the output transformer seciondary (green/yellow wire) thru a series resistor of 22K ohm to the tip of the output jack. A 270 ohm resistor is tied across tip and ground of the jack. This is a padded output right off of the output and should work pretty well. I had a 135 watt model in a while back and tried the line out to a Peavey KB400 amp, power amp input. It was great! Looks like a 4 ohm speaker (Peavey 1501-4SB) would be a good choice. You can get a baffle with aged cloth made at Mojotone. Your baffle may not be removable. This was the case of later 70's amps. The baffle board on early models was screwed in. You can get a Repro Vibrosonic cabinet from Mojotone and just slip the chassis in it! They are over in Winston Salem, NC. [This message was edited by Ken Fox on 07 October 2002 at 07:42 PM.]
