I was wondering if I used Y connectors at the power amp and ran ics from both the pre and HT receiver to the amp that way if it would work better than a speaker switch
No, it would not be better than a speaker switch as whichever was feeding the amp would see the high impedance at the amp input in parallel with the much lower output impedance of the other pre out. The resulting impedance would be much to low to perform properly.
However, you can use a high quality line level selector switch between the pre outs and the amp inputs. In that way you can easily select which pre outs is feeding the amp.