How to go from RCA to XLR?

Rwwear, the traditional method of monostrapping a tube amplifier is to put the two channels in parallel, rather than in bridge mode. You put a 'Y' adapter into the inputs, and then parallel the outputs. The output impedance is cut in half, so if you are using an 8 ohm speaker you use the 16 ohm taps.

So whichever output tap you are using, you will need a jumper to go from the left to the right for that value, for example for 8 ohms you put a jumper from one 16 ohm tap to the other, and then the speaker will connect from either 16 ohm tap and Common.

This will not work for transistor amplifiers, which have to be bridged. You could bridge the Citation as well, but at the minimum you would need an input transformer to convert from SE to balanced, or a converter circuit to do the same. Your output connections then would be the taps themselves- C would be ignored, for 8 ohms you would use both 8 ohm taps, one channel would be the 'plus' and the other would be the 'minus'. I think the monostrapping technique is easier.

Thanks Atmas. But why can't I use one channel of the amp for the positive input and the other for the negative of an XLR to convert the amp to balanced? I would use the chassis for ground.

I think his last paragraph confirms that you can.

Regards,
-- Al

I don't see why I would need an input transformer Al.

You wouldn't, but if you don't use one *and* you don't have a balanced source, then you'll need some sort of inverter circuit for the inverting channel.