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As preamp. Most affordable amps under likely desk-top consideration run a passive pot, not dedicated preamp stage. Adding that missing stage improves performance nearly invariably. The challenge is to identify the external box that's priced in line, has sufficient features and nets demonstrable upgrades. Keeping it simple is a big concern with such systems. One more box means one more interconnect, one more power cable, less precious real estate. The HDP's feature set and minimal footprint quite offset these liabilities. How about demonstrable sonic upgrades? With the Dayens Tizo's 84.5dB rating less copasetic with the APPJ/MiniWatt EL84 SEP than my usual 5 SAT, the era designs hopped on my Ikea plate-stack kitchen ware. With the APPJ's pot at max (i.e. bypassed), the HDP's own attenuator sat between 10:30 and 11:00 for headroom galore. Without the NuForce, the tube mini with updated Synergy Hifi glass sat at 10:30 to 11:00 also on its own dial.

Interesting. On languid flow—what I secretly call the waft & wane factor to conjure up visions of lapping ocean surf and surfaces in flux—the amp-direct feed was superior. Things were less grippy, the bass was a bit looser and less prominent but on female vocals with piano, upright bass and such, I actually preferred the valve amp pure. Because the ported era design speaker is deliberately beefy in its response, the active preamp contributions pushed this aspect too far on the type material where bass is background accompaniment, not foreground sensation. Quite unrelated to my personal response, it was clear as day that the NuForce addition did very specific things and was far from subtle about it.

Predictably the tables of preference turned with my favored organic ambient fare like Mercan Dede's Su, the Tulku canon, Bob Holroyd, Gaudi, Hector Zazou, Lisa Gerrard and similar. Here infrasonics feature strongly and are vital to both the very clever multi-layer soundstages the DJs or recording engineers have composited in the studio and the seductive lounge flair of groove such music thrives on. By elevating LF amplitude and overall grip, the NuForce addition won hands down. It didn't introduce any noise whatever. What did shift was subjective perception of resolution. Because the sonic fabric filled out and became more substantial, less wispy, the focus on fine detail was turned. It was still present. The obviousness of said detail was simply traded for greater mass and impact. A side effect thereof was a certain oppressiveness at higher levels. The sheer intensity of well-recorded stuff with very low bass became nearly too much in such nearfield distances but was easily adjusted by lowering the volume. The valve amp pure could be listened to at higher levels before the ear/brain 'overloaded'.

The Dayens Ampino was next. Volume controls for both amp and preamp again were matched but this time sat at 10:00 respectively. On all other matters, it was a complete rerun. Perception of fine detail as led by the treble's balance was higher going direct. The NuForce downshifted the tonal balance by building out bass power and midbass dynamics. The center of gravity was lower, mass higher, treble prominence lower. The Ampino solo was leaner and wirier. Ampino + HDP were warmer, weightier and generally more robust and articulated.

The verdict was simple. The HDP as active preamp did exactly what it should have done. Whether that material filling out and dynamic expander action will always be what's desired is a different issue. More is not always more. If you're energizing a bigger space than the single square meter of the usual desk top, I can pretty much guarantee that you'd prefer your T-amp or equivalent speaker engine preceded by the NuForce. Woofer control and extension from a given box become more relevant as more air has to be moved. On the desk top, your existing amp+pot rather than true integrated may not need more meat on its bones if your preference is for air over density, litheness over wallop.

: One of the great joys of PC audio is YouTube to scout for new artists. Admittedly frustration can soar high when you can't locate a proper CD or download file for that stupendous performer in a restaurant taped by a friend. But resourcefulness is a virtue. The point is, a USB port is not only for serious listening. Half the fun comes from amateur or preview sources. That's how I discovered Bülent Altinbaş' Buğu. has it and many other Turkish pop albums for previews in their entirety. Thanks to Hakan Cezayirli, editor of Turkish online magazine, I now own a proper copy of Buğu and three other Anatolian clarinet CDs. For a real-world USB assessment, I began with the Buğu MP3 feed on "Unutama Beni", toggling the Entreq USB link between iDecco and HDP ports.

The iDecco's path had far more gain. I had to mark the necessary volume correction exactly (nearly 180° on the HDP's pot which was master also over the iDecco's fixed output). Peachtree Audio's converter and USB transceiver interface implementation (or their analog output stage) were modestly superior in similar ways to the previous with/without preamp test, albeit with a rather smaller lead. The iDecco was 'with' - more tonal substance, fuller colors particularly from the upper midband upwards and a stronger foundation. The NuForce was a bit leaner. Particularly in the critical higher bands where MP3 compression gets blatant, it was more brittle and whitish when Kirpi played his blackwood in its upper third octave. Ditto for the kanun tremolos. Time for my MacBook and uncompressed files.

This was the second rerun, albeit with a shifted emphasis. With uncut data density, the difference between the iDecco and HDP as USB processors now hinged on the softer/crisper axis. The earlier leaner/fuller balance of the MP3 interlude no longer qualified. Its specter of leanness no longer factored. What now distinguished the A/Bs was greater articulation for the iDecco and a softer handling of the attacks for NuForce's unnamed chip (the earlier hint of four paralleled DACs suggests the 8-channel Sabre in fact so the difference I heard will have been primarily a function of the respective analog output stages). I no longer had the HeadAmp Pico with USB DAC on hand but my educated guess is that it and the NuForce are very competitively matched for their converter functions. Versus the iDecco, the HDP was bested by a clearly far smaller margin than as dedicated preceding preamp, it bested my integrated amps with their passive pots run solo.

Adding up three rounds: In pretty much all reviews I've seen on them, the authors sequenced the relative quality of the various functions of the various Peachtree Audio integrateds from good, better, best as power amp, preamp and DAC. What far exceeds the price of the Decco, Nova and iDecco is their D/A converter quality. With the NuForce HDP, my read turns that on its head. The equivalent sequence of good/better/best becomes USB DAC, preamp, headphone amp. The conclusion is obvious. The crown jewel in the NuForce Icon range perfectly fits our definition of a realsization component. The crown-jewel application for the HDP is as headphone amplifier where it competes directly against acknowledged greats and drives anything you might throw at it. That it costs less than many of them but includes multiple inputs, a pre-out and a USB DAC goes those extra miles deep into Realsization turf as an aggressive recession buster and talented multi tasker. Really well done!
Quality of packing: Good.
Reusability of packing: A few times.
Ease of unpacking/repacking: Child's play.
Condition of component received: Flawless.
Completeness of delivery: Includes SMPS power supply, 6.3mm-to-mini adaptor, mini-to-Toslink adaptor, white silicon stand.
Website comments: Good but up for an overhaul shortly to make reviews and user feedback easier to find.
Human interactions: Always responsive.
Pricing: High value.
Final comments & suggestions: If you have a T amp, Ampino or similar and want to add headphone drive, the HDP becomes a 2-for-1 by also upgrading your amp's speaker drive with the usual active preamp advantages. As possibly a shift in the NuForce house sound, the HDP combines the usual high contrast ratio detail with a new and very cleverly administered warmth which adds some fullness or density but doesn't slow anything down. The noise floor is very low and forum posters report excellent results even with high-sensitivity IEM headphones.

NuForce website