I upgraded to an XT derailleur and cassette. However, I'm still using my old Alivio trigger shifters. The chain seems to be misaligned when shifting into low gears, making the "I'm about to shift" noise and giving off a perceptible vibration. Is this due to the new cassette, an improperly installed cassette, or incompatibility with the shifter? Thanks in advance.
There shouldn't be a compatibility problem with that setup (Alivio 8 sp shifters, XT 8 sp cassette and XT RD). If you're still using your old chain, it may be that your old, worn chain isn't meshing properly with the new cassette, causing skipping and noisiness. If that's the case, replace the chain and that'll probably fix it.