I agree with Jamato8 comments. I have heard 3 (not quite 5
) versions of the Reference. At the moment one has about 250 hours and the other 200 hours, frankly it is very hard to tell them apart because of the wide swing in changes from one day to the next.
One day the bass is tight, pronounced, and the next it changes. One day the treble is clear, detailed, and the next not so much. There are two constants though, first the soundstage it is huge both left to right and in depth. I have said that it almost seems like you have two amps inside the reference one taking the main center and a second for the extreme L/R. The second constant is the clarity, I hear bells and hi-hats that all other amps (except the Supermicro IV) simply can not reproduce.
Next Saturday I hope to get together with Vorlon1 and compare some amps. The only thing that would hold be back is that neither of the Reference Amps will have 400 hours (one will be very close). I have had two other portables with large caps, The Hornet which took 400 hours and the Tomahawk which took 800 hours. Time will tell how many hours the reference needs.
Meanwhile I am eagerly awaiting the 400 hour mark.