power xm, sirius, 2004 civic ex

Some details: 2004 Civic EX Installed: Pioneer DEH-P3900MP HU Stock speakers Pioneer SIR-PNR2 I recently picked up a Pioneer GEX-P920XM tuner for XM Satellite. I installed the HU and Sirius tuner at the same time and wired them together for power. Works great. I originally planned to splice into my lighter adapter for power for the XM Tuner, but remembered it's not a source of constant power like the tuner requires (would lose presets). Would adding the XM tuner's power line to the HU/Sirius splice be asking too much, or should I be fine?

It shouldnt make a difference at all. Think about it.... you cant use them both at the same time so splicing wouldnt make a difference. Just make sure you have the units grounded properly