To a casual observer, the Revolution 7.1 might look like a low-end sound card rather than one that supports high-precision output. The card itself is quite small, and could easily be mistaken for Hercules' Gamesurround Fortissimo III 7.1.
Looks should be the least of one's concerns when purchasing a sound card, but a quick glance at the board does reveal a few missing features that may be important to some. Unlike even many low-end sound cards, the Revolution 7.1 doesn't have internal connectors for auxiliary devices like CD or DVD-ROM drives. Personally, I tend not to bother with internal sound card connectors, but some users may find the omission limiting.
Looking at the Revolution 7.1's collection of external output and input ports reveals one area where the card's lack of internal connectors could be potentially damning: digital audio recording. The Revolution 7.1 features a coaxial digital output port, but no digital input port, which limits the card's recording capabilities unnecessarily. Even some integrated motherboard audio solutions feature digital output and input ports, which makes the Revolution 7.1's absent digital input port especially disappointing. I wish the Revolution 7.1 had at least an internal connector where one could potentially wire up an auxiliary digital input.
Apart from its lack of a digital input port, the rest of the Revolution 7.1's port cluster is well-equipped. The card's digital output is coaxial rather than optical, which is an interesting decision since optical S/PDIF ports seems to be all the rage with sound card and motherboard manufacturers these days. Since I don't have home theater equipment or speakers that support either digital standard, I don't really prefer one over the other.
I do, however, have a set of headphones, which means I am affected by M-Audio's decision to have the Revolution 7.1's headphone jack share a port with the front channel output. To use my headphones, I'd have to go crawling around in the tangled mess of wires under my desk just swap plugs. Because the headphone output is shared with the front channel, using something like a 5.25" drive bay insert to move an audio port to the front of a case isn't exactly a workable solution, either. I'd wager that few users are going to take full advantage of the card's 7.1-channel audio support, so it would have been far more convenient for the headphone jack to share a port with the extra rear audio channel.
Under the hood, the Revolution 7.1 is powered by ICEnsemble's Envy24HT audio chip. ICEnsemble is owned by VIA, and VIA is now marketing the several flavors of the Envy24 for different markets. The Envy24HT is the top of that line, with support for 24-bits of internal precision at 192kHz across 8 output channels.
AKM's AK4355 digital-to-analog converter (DAC) maintains the Rev's 192kHz/24-bit precision all the way to its output ports. The AK4355 was originally indended for high-quality DVD audio playback. Since the DAC supports 24-bit audio at a maximum sampling rate of 192kHz, the Revolution 7.1 doesn't need to downsample the Envy24HT's digital output before converting it to analog signals for the card's speaker ports.
The AK4355's rated signal-to-noise ratio is actually a little lower (106 versus 110dB) than the AK4524, which is used on Terratec's DMX 6fire 24/96. The fact that these two cards use different DAC chips suggests that they might not sound as identical as I had hoped.