Best to connect both dac and analog to one amp

I have a PS Audio dac with its own volume control and a Lamm LL2 pre amp which I use for my analog rig. I want to connect both to my Plinius SA-102 amplifier. Obviously I could run the dac through the preamp but 1) it sounds worse than running the dac direct, 2)why mess with 2 different volume controls and 3)why turn on the Lamm and put unnecessary hours on my new old stock Telefunken tubes.

The Plinius has inpus for XLR and RCA so I could use one for each but the switch for this is on the back of the amp (inconvenient to reach) and also has options for running either input as stereo or bridged mono, so I'd have to reach around and pick the right one without being able to see. All I need, I guess is a high quality passive switch. Any suggestions?