HeadRoom Supreme headphone amplifier Page 3

Well, used as a simple amplifier, the HeadRoom stomped all over the Advent. The AC-powered receiver's bass sounded lumpy and spongy compared with the little battery-powered amplifier. This was probably due to the Advent not having a true headphone output, instead padding down its speaker-level outputs with series resistors. But it sounded so grainy in the highs compared with the HeadRoom that I ultimately ruled it out of contention.

The Denon CD player, on the other hand, has a surprisingly good headphone output, capable of driving Sennheiser '580s to moderately high levels without strain. However, it didn't go as satisfyingly loud as the HeadRoom. With levels matched at 1kHz, the CD player sounded rather thin compared with the separate amplifier, lacking both the HeadRoom's bloom and its clarity. Its midbass also lacked a little definition, the HeadRoom sounding considerably more authoritative throughout the bass due to its greater low-frequency extension and power reserves.

Against the mighty Melos SHA-1 I habitually use as a preamplifier, however, the match was more even. The tubed preamp sounded warmer in the lower midrange, the solid-state having more apparent clarity in the treble. Surprisingly, given the 6DJ8/6922 tube's reputation for having a rather bright character, the upper midrange and lower treble of the two amplifiers were very close in tonal quality. Where the Melos walked away with the honors, however, was in the feeling of unrestrained power it gave to low frequencies. Where the HeadRoom scored over the direct output from the CD player was where the Melos went even further. Recorded bass drum gave more of an impression that it was going to smooth out the folds in your cerebellum (footnote 6). But all things considered, the little HeadRoom still gave a very good account of itself in this exalted company.

How about HeadRoom's Process process?
With early versions of the HeadRoom, I couldn't get past the bass boost applied to dual-mono signals to appreciate any changes in spatial perception. With recordings with a strong low-frequency mono content—virtually all rock recordings, which have the kick drum and bass guitar panned to a central position—the sound muddied up to the point where I preferred using the unit as a straight amplifier. With the current versions, while a warming-up of central images was still noticeable, this didn't get in the way of other aspects of the sound.

Well, to my surprise, I didn't get the out-of-the-head, binaural-type imaging from stereophonic recordings that I expected from reading both HeadRoom's literature and the original Bauer and Thomas papers. (Neither did '60s HFN correspondents who had tried the Bauer circuit, as I later discovered.) What I did get was a more coherent presentation of the soundstage within my head. Off-center images didn't seem to clump at the far-left and -right positions as they did with straight headphone listening. Simple recordings made with a spaced pair of omni mikes lost some of their characteristically unstable center imaging, and far-away soundsources captured by this mike arrangement did appear to come from behind my head.

But this making-more-coherent factor was, at best, rather subtle compared with the tonal changes. Simple A/B-switching on the fly paradoxically made it harder to detect. Switching the Process in or out, then settling in to appreciate a recording's gestalt, was much more effective in revealing its effects. Chronicles, the excellent collection of Stevie Winwood classics (Island 9 25660-2), provided a suitable test circuit for the HeadRoom to negotiate, with its combination of driving bass guitar and bass synth coupled with rather hashy high frequencies.

With the Process bypassed, I was all too quickly annoyed by this disc's treble quality (though the Sennheiser HD-580s (footnote 7) alleviated this considerably compared with the earlier '560s or Beyerdynamic DT901s and '911s). With the Process engaged, there was a satisfying solidity to the music's presentation which made the album much more listenable. Ambient information, too, seemed to be more coherently associated with the sound sources exciting it, giving rise to a greater sense of realism to the image. In this respect, switching in the HeadRoom's Process made its musical presentation more believable, in the sense that the unprocessed Melos's presentation was more tangible than that of the unprocessed HeadRoom (or the same sense that LP is, in broad terms, more tangible than CD). Given the choice between the Melos driving the Sennheisers and the processed HeadRoom, I'd opt for the HeadRoom.

True binaural recordings—such as one I made at the final hairpin of the 1992 Montreal Grand Prix, and which I shall include on Stereophile's forthcoming Test CD 3—reproduced in the Bypass position with a true sense of the sounds taking place outside the head, of the listener being immersed in the acoustic environment. Front-placed images, however, as always appears to be the case when a generic dummy head is used (footnote 8), were perceived as being positioned in my temples rather than in front of me. Switching in the HeadRoom Process appeared to have no effect at all on this recording, even though the recording time and amplitude cues were then effectively doubled.

Overall, my time spent with the HeadRoom amplifiers was very satisfying. I spent a lot more time listening to music on headphones than I had done before—always a sign that something good is going on.

Summing up
With some products, to see them is to want to possess them; the HeadRoom headphone amplifier falls into that category. It also sounds superb. Even though I couldn't produce any significant out-of-head imaging with the Process switch engaged, it did sound more natural on nonclassical recordings. Don't bother with the Standard unless you're really strapped for cash. Buy the $299 Premium if you don't need the HF-boosting capability of the Filter; otherwise do what I'm going to do and spring for the $399 Supreme. A remarkably well-thought-out, well-engineered product at an excellent price. Long-distance travel will not be the same again. Highly recommended—give that 800 number a call!

Footnote 6: Readers should be warned that the enhanced loudness capability of the HeadRoom makes it even more important to take care about how loudly they listen to headphones. I'm concerned that an entire generation is reaching adulthood with crippled ears, due to their habitual playing of portable tape and CD players at hearing-damage levels throughout their teen years.

Footnote 7: I'm much more impressed with these headphones than Alvin Gold appears to be in this issue's "Industry Update." Yes, they sound very smooth compared with earlier Sennheiser cans. But the lack of aggression is due to their more natural presentation of high frequencies, not to a lack of pace. I accordingly used the '580 headphones for monitoring during Stereophile's most recent recording activities (see this issue's "As We See It").

Footnote 8: Recent research suggests that this is because the brain is very sensitive to the response-shaping effect of the ear's pinnae. Binaural recordings made with probe microphones actually placed in the listener's ear canals don't suffer from this frontal image collapse—for that listener only!

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