Joelv: I'm using MIrage OMD-15s.
I would describe them much like you described your Triangles--efficient (91 dB, 1w @ 1meter), just the slightest on the warm side of neutral, and very revealing as well. I can easily hear differences in cables, power cables, amps, preamps, etc. upstream. In addition the Mirages are forward-biased omnidirectionals, so their in-room power response is very uniform throughout the room.
This amp/speaker combo is plenty good to fill the listening space, with is a vaulted ceiling, open architecture living area, comprising the living room (about 16x19), entry hall behind it (with only a waist-high counter between), and dining area that's an open area off to the side.
When this amp is breaking in, you are fully aware that you are listening to digital solid state. But when it passes 130 hours (and assuming you have a good matchup with your power cord), it is hard to say what the topology is, because it has that low-level organic flow reminiscent of tubes and the speed and clarity of really good solid state without any etch or harshness whatsoever. In my rig it is astounding in its bass performance in areas of clarity, fullness, pitch accuracy, and extension. That's not to say it's weaker in midrange or treble; it's exemplary in both. It's just that it's so rare to hear this level of bass resolution that it stands out and is one of the first things people notice.
This amp is so good, it's hard to keep from sounding crazy with hyperpole. I know that the VTL Siegfried and Reference amps are better, and more powerful amps will have a broader operating range, but soundwise, there are very few other amps I can say with certainty sound better than this one.
Oh, and since your Triangles are super efficient, you will be pleased to know that this is the quietest integrated or amp/preamp combo I have ever had. Robert Deutsch, who reviewed this amp for Stereophile, tested it powering a pair of Avant Garde horn speakers. Because of the Avant Gardes' incredible sensitivity, he was accustomed to chasing down hums and buzzes when testing various upstream electronics. With the Onkyo, his reaction was, "Is it on?" It was.
Although both the Onkyo A-9555 and Outlaw RR2150 are Stereophile Class C recommended components, the Outlaw shouldn't be mentioned in the same breath as this amp.
