The Fifth Element #16 Page 3
The Grace 901 is approximately one professional rack unit high and half a rack unit wide. It is 8.5" deep and weighs about 6 lbs. The front panel is thick aluminum, polished to a high gloss. Front-panel controls are, from left to right: stepped resistor volume control, additional gain, digital or analog source, digital sampling rate (32-96kHz), two standard phone-plug headphone jacks, and power. The additional gain, input selector, and power switches are illuminated buttons of the sort I refer to as being of the "Ph.D." variety, as in: Push Here, Dummy. Gotta luvvit.
On the rear panel are an IEC inlet for the power cord (no plug-in transformer); optical, S/PDIF, and AES3 digital inputs; and left and right RCA and XLR analog inputs. Industrial design and fit'n'finish are surpassed only by the likes of Nagra and the Jeff Rowland Design Group, which means that just about everyone else was left in the dust miles behind. Meanwhile, the 901 just sits there, quietly screaming professional competence (in an elegantly understated way).
The only thing I can't figure out is the threaded hole in the middle of the bottom panel. For mounting on a mike stand or camera tripod, perhaps, for musician foldback at sessions? (footnote 3)
It is the 901's ability to take a high-resolution digital input that distinguishes it from most headphone amplifiers. The 901 accepts digital inputs from 32kHz to 96kHz, and indicates the sampling rate with front-panel LEDs. Apart from the convenience of needing only one signal cable, having one's headphone amp provide an internal DAC of known quality removes two variables from recording system monitoring: an outside DAC and its interconnects.
The Grace 901 performed flawlessly. Its only quirk was a slight pop on power up and down—but no headphone amp should be powered up or down while anyone is wearing the headphones anyway. The 901's essential sonic character was refreshingly rich and full-bodied, without being sludgy or lacking detail. Perhaps what I was hearing was equally attributable to its power reserves. I can't say for sure. But its circuit is based on a telecommunications current-feedback amplifier chipset that can drive five miles of copper wire if it has to, so 10' of headphone cable was doubtless a snooze.
Perhaps it's just me, but fine as the Grace's internal DAC was, I preferred by a slight margin the sound of its analog inputs when connected to the Marantz SA-14's analog outputs by Stereovox analog interconnects. Yeah, I know—for $2500 a meter pair, they should sound good.
A headphone amp is pointless without headphones. My rough'n'ready Audio-Technica ATH D40s are distinguished more by their relative indestructibility than by any excess of subtlety. Sennheiser kindly lent me a pair of HD 600s, a Bob Ludwig fave. The HD 600s balance delicacy of detail with dynamic range and bass extension, which goes a long way toward justifying their $450 price.
It appears that for every pro user who auditions the 901, two buy it, so there is that. But that doesn't answer the question whether—massive coolness factor aside—it's a good use for that spare $1500 you just happen to have lying around. The answer, as usual, is: It depends.
The 901 is built like a brick, is quiet as a mouse, and is very relaxing to listen to. However, it's a pro unit that was designed to let you hear a mike feed or do quality control on a mix or a mastering job. (Bob Ludwig bought five 901s for Gateway Mastering and DVD, which should tell you something.) The 901 therefore lacks the frequency, temporal, or cross-feed processing functions that other headphone amps offer as means of trying to make the headphone listening experience more like listening to speakers in a room. I don't mind the "inside the head" effect of listening to non-binaural stereo recordings on regular headphones, but it's your call. Whether or not the 901 is for you probably comes down to how much headphone listening you do.
Footnote 3: My two goals in writing are to amuse John Atkinson, and to convince him that I have actually removed the piece of gear in question from its box.