When I have to practice songs for my cover bands, I use either an MP3 player loaded up with my band play list or a CD player running into a Korg Pandora PX-3 headphone amp (for digital transposing only) into Mackie 1402 VLZ Pro mixer into a pair of Mackie MR5 powered monitors. You can hear how the music will be slightly out of tune sometimes and I can adjust the digital transposer to "tune" the music to standard pitch or can adjust the music to key that my singers sing in.
I run my guitar into a Zoom G9.2tt effects processor (effects in front of MP-1 preamp & MIDI controller), an ADA Depot 3TM mod MP-1 preamp, Rocktron Intellifex (delay/chorus/reverb) into a Digital Music Corporation System Mix Plus which I run into the mixer in full stereo. If I want to do acoustic guitar playing, I'll use my Ibanez Prestige RG-2020AX guitar through a Fishman Aura Spectrum DI box into the mixer as well.
Guitar George