Looking for a tube preamp with remote control.

Simple set up. Two additional short I/C's to and from tape out/in and plug it in. When you want to use it you just switch to 'tape in'. If you want to hear it without the remote you simply switch back to 'source'. FWIW I used a Placette which is a high quality one at a moderate price. When you can find one used it sells for about $600 +/-. There are different models but the one you would want is a single source unit. (They also make a unit which allows 3 sources and they have an active unit as well (very expensive).

Why not just get an add on passive remote control and insert it into your pre-amps tape loop? Worked well for me.  A good quality one will not change the sound of your system.