Never plugged 'phones into a dedicated outboard amp? Considered the op-amp in your receiver, integrated or source component perfectly adequate, not a mere afterthought ? Well, the difference is exactly like going from a so-so asthmatic receiver to a powerful amp with the lungs of a Tour-de-France champ. He has the reserves, power and control to climb endless hills. Such an amp relentlessly clamps onto the woofers without thought of letting go. What was flabby and indistinct firms up, what was cardboardy fills out, what went "poof" now goes "pop".


A good amp will also banish the tin and tizz on the top, render voices more convincingly, add detail like a hi-rez printer fills in pixels and inject a certain drive into the music, as though the tunes' tempi stopped dragging and actually pulled ahead.


The headphone jack in most receivers or CD players is really more of a headphone hole than focused output. Through it drain most the vibrancy and full-blooded excitement that your speaker system might already deliver. Exactly how much is flushed down that hole was brought home comparing MOH with the jack in my CDR-630: Things got louder. Now, if you've diligently matched playback levels, they're not really louder. But it sure seemed that way because I heard more - more trees in the forest, more spots on the trees.

It was akin to rousing the main rig past its "daydream" threshold of polite background levels. The curtains open, fresh air enters the room, the sound arrives from top to bottom. Beyond that point, things merely get louder. Below this threshold, fullness shrinks back into two-dimensional flatland. And flat is what my regular headphone jack sounded like by comparison - plenty loud enough but flat.


The second thing of note was much more acute separation. On the Take 6 album, Alvin, Cedric, Joey, Mark, Claudie and David decongealed from an amorphous blob of voices into distinctly separate performers, much like a Polaroid shot acquires depth while you watch it develop. And while headphones don't soundstage like speakers, MOH's superior crystallization of individuated musicians created a much more convincing illusion of illuminated stag

Bass underwent the famous Professor Klump to Eddie Murphy transformation - from soft, pudgy and nice to lean, mean-spirited and full of violent energy. Klump's height equaled Murphy's. MOH's bass didn't go any lower either. But the body fat count sure dropped like the stock market to add definition, finesse and nimbleness of motion.


The telltale sign of artifice -- the CD player hole's tizzy, etched treble that always cast a certain whitish chalk dust over the music -- evaporated. It was replaced not with warmth but expansion, as though slipping into a glove to fill it out to the very tips extended the fullness in bass and midrange into the upper vestiges of the high end.


This is exactly the kind of transformation a good headphone amp should make. Did it leave any stones unturned though? A comparison with the MGHead and RA-1 would answer that - on a basis obviously limited by the number of components I had for comparison.

Still under the funky spell of Take 6 (which put a new spin on digging a funky mood) I let the disc play and alternated between both amps using the HD-600s. A brief pause allowed to swap interconnects and resume listening within seconds. The differences were less than expected. It made me wonder whether regular amps would sound far more similar if the aberrations of the speaker/room interface were eliminated.


Once levels were equalized, the first quality of distinction -- and it wasn't pronounced -- were MOH's slightly more defined leading edges. Calling the MGHead's attacks minorly fuzzy by comparison is still an overstatement but at least suggests the proper direction. If one grain of salt fit on MOH's edge, the Head perhaps accommodated two. This small difference was easiest noted in Markus Miller's various percussion hits and thigh slaps (the guy's gotta have legs of steel and hands of wood to produce such cracks). The MOH was a bit crisper, sharper, the Head's attacks rounder, sanded over gently with fine-grit paper.


The second difference was in the voices. Here the little Head produced some of what bigger tube heads call modest saturation - a harmonic richness that bestowed a faint sheen or glow to the midrange. Again, this was far less developed than what I've heard so often over speakers. The Head didn't up the ante in the SET-typical immediacy department. After all, how much more immediate can one get than having sound broadcast directly into the head? Voices just acquired a bit more timbral robustness - in fruity terms, a few more days of sunshine to raise the sugar content of complete ripeness.


Returning to MOH now strapped to the Grados had a very similar effect - things turned a fraction more "midrangy" yet, the sharp-edged snap lost some more of its bite. Taking the Grados to the Head (do cans pee?) went even further in that direction. Attacks fattened and mellowed, rhythmic urgency relaxed. Very seductive but probably veering from honesty a smidgen farther than an entirely harmless white lie. That difference -- Grado/Head versus Sennheiser/MOH -- was now rather pronounced. It recalled the stereotypical "solid-state precision" versus "tube warmth" rhetoric.


For verification -- or another Q-tip -- I reversed the setup. I now pitted the Grado/MOH combo against the Sennheiser/Head rig. The differences between either were again more subtle, no longer in the hit-you-over-the-head black or white category but a matter of temperate shades and hues.

Suffering the assumption that the Grado amp was designed foremost with Grado's own phones in mind, that's what I used in the first go-around. The main difference of the RA-1 was one of heightened "suchness" due to the eerie quiet of its DC battery supply. Let me explain. MOH performed quietest in my rig when I defeated its normal ground lift mode - engaged, and with the attenuator wide open, I heard what sounded like power supply grunge. Flicking the switch eliminated it like magic for dead quiet. Still, and without signal, the quality of silence between both amps exuded a different gestalt. MOH's silence was audible in the subliminal dither way that, multiplied to eternity, we talk about as silence so thick it's deafening. A silence of presence.

RA's silence was inaudible, a vacuum or black hole. Under signal, this utter absence of background mist deepened contrast. This had a slightly different aspect than MOH's prior added crispness of edge definition versus the Head. The word that suggested itself for RA's edge over MOH was stepped-up clarity, the removal of a thin film of opaqueness that became appreciable only in its falling away.


Things now did sound a bit more immediate yet. If I were an RS-1 owner deciding between either amp, I'd give the nod to the matching (and far cheaper) wooden box. You'd forego processor function (more on that in a minute) and preamp option but gain portability - being small and battery-powered makes the RA-1 the perfect on-the-go companion for truly outstanding High Fidelity sound. Muscular. Colorful. Vibrant. Direct. $350.

What if you're a Senn fan? Does the RA-1 drive this more complex and inefficient load as well? It drives it just fine, and with output to spare. But, the tables do turn. MOH gains the upper hand, sounding as though it exercised added control to, once again, drive home that outstanding crispness that seems to be one of its core traits. It's a subtle improvement and not of the sort that would make an RA-1 owner with HD-600s feel gypped. Still, in the audiophile race for incremental brownie points -- mere crumbs at times but chocolate is chocolate to those who care -- MOH's presumably heftier power supply seems the slightly better mate for the Sennheisers.


Now flip the virtual pages once more for a quick lowdown on MOH's processor function and the three cable options for the HD-600s. Incidentally, those (stock, Clou and Stefan AudioArt) omit the Cardas wiring harness that Tyll tells me is in perennially short supply because - a/ it's a pain to build, b/ Cardas isn't convinced many of them will sell, c/ whatever supplies Tyll can talk George into delivering sell out regardless. Tyll claims it rather goes beyond the Red Jaspis he sent. But, he didn't have a single Cardas left and wasn't sure when the next run would arrive so I'd do without to get this write-up wrapped up.