I had the same experience as Tcowden and went with a dedicated Square D QO box and breakers as well.
This year was the third time that I have installed dedicated circuits in a house for my system. This time, I not only went with a separate dedicated better quality panel and breakers, I split the electrical system a few inches past the meter into a 200-amp house system and a 100-amp AV system. The dedicated AV cable from the meter to the AV breaker panel is an 85-foot length of armored 0-awg copper cable cooked and cryo'd by Virtual Dynamics and the 5 dedicated cables from the AV breaker panel are armored 10-awg cables to the Virtual Dynamics cooked and cryo'd Hubble hospital receptacles (1 for each of the mono blocks, 1 for the analog gear, 1 for the digital gear and 1 for the projector. The 0-awg cable (expensive) was used primarily to prevent a voltage drop on such a long run.
This was not inexpensive, but the result is well worth the cost. It took my system to a level I have not previously experienced in terms of how silent the system is save for the actual music. The system is very relaxed and powerful, but the thing everyone notices is the width and depth of the soundstage, 3 diminsional imaging of every voice and instrument, the clarity of low level detail and the extended decay of notes, the easy ability to distinguish different guitars and strings. I cannot recommend this dedicated cabling too highly.
Best,
Ed