yes it accepts 110-220 volts. it is quite a huge power pack with 32 volts similar to those of big notebooks, you just need another 3-pole wire like that one, as it is deattachable:
or you just use a plug-adapter.
btw. the slimstage is a discontinued model, maybe therefore the prices are so low here in europe, they are trying to get rid of them.
the slimstage is not produced by soundmatters anymore. i had some email-chat with soundmatters-support and asked them why it was not that popular. they told me that it appeared just when the financial crysis started and at the same time the TV-sets got even slimer, so the slimstage was not that "slim" anymore. they don't seem to have had much success with it, despite it being a really great performer.
soundmatters is already devoloping a new model which should be 1 1/2" deep including the wall mounting. they will still be using their proprietary driver-technology as well as passive radiators to deliver a full-spectrum sound without the need of a subwoofer.
if you want wall-rattling sound you might indeed want to add a separate sub, but for our bedroom we are more than satisfied. the 10band EQ is quite versatile. i cranked up the lowest band (31hz) to the max, this enhances more of the deepest frequencies than the rough bass-adjustment. i found that bass turned up to +5 with the added EQ-adjustments makes the sound really deep and full without sounding boomy or flabby. bass response also seems to be very dependent on the positioning. i noticed that when in bed (near the rear wall) i have a perfectly deep bass, but standing in the center of the room the bass disappears (probably due to cancellation of phase-inverted waves-reflections). funnily bass is really dominant if listening from another room. it sounds as if having a huge setup and actually seeing that the sound is coming from a rather small bar makes one surprised.
i still haven't explored where the limits of the slimstage are. although i cranked it up quite loud (already too loud for pleasant listening) it still didn't distort even with my heavy EQ-adjustments. the maximum volume is 99, i already had it turned up to 70 and this was pretty loud, you could hear (and feel) it in the entire house (especially bass), really surprising for something without any subwoofer or large drivers. but soundmatters was always using passive radiators for extra-punch instead of usual bass-ports.
the built quality is very good. the enclosure is nearly completely out of metal, there is not much plastic around. it feels quite heavy and sturdy. this is not a "cheap" product, but really gives you the impression of high-grade quality. for the price i paid it was a real bargain! i wouldn't have paid the original 899$ though.
i really wonder how the 50" model sounds as it has an additional bass-woofer with 2 passive radiators, but as it seems now, i won't find any.