Use of Y connector rather than passive preamp

I get way better sound when my DAC with volume control is directly cabled into my power amp than when it goes through my preamp. I also like the sound of my phono pre directly cabled rather than going through the same pre (though the choice is not as clear). I basically need a switch with volume control on only one input. A passive pre could do the trick, but there is a lot of discussion re qualities of different designs, and I imagine directly cabling the DAC to the amp would beat interposing any switch/volume controller. To minimize impact on the DAC route, can I use a simple Y connector at the power amp, with a volume control on the phono pre side? Is there a danger if I accidentally have both inputs on at once? Perhaps the impact on sound quality will be minimal if I use a passive pre and just turn the volume to full when using the DAC? (RME ADI2 DAC, Parasound JC3+ phono pre, McIntosh 462 power amp, ARC LS25 II pre, all balanced connections). Thanks a lot for your help!