Review: Wyred4Sound STI 500 Amplifier

Category: Amplifiers

I directly compared a Wyred4Sound STI 500 against an Audio Research Corporation SP9 MkIII pre & Wyred4Sound ST 1000 power amp; and, for what it’s worth, an NAD C325BEE intergrated. The source was an ARC CD1, and the speakers Usher Be-718s and a REL Stampede sub-bass. My previous amplification, which I’ve heard in the same system, was a Jadis Orchestra Reference. A standard Oppo BDP-83 was also used.

Overall the STI 500 is an amazing amplifier. Using it as a preamplifier for the ST1000 saw little change to the overall sound – so for mine the ICEpower modules have a very consistent presentation, whether you choose the smaller or larger of the two. The main point of the comparison came down to whether the preamplifier section was competitive with the ARC SP9MkIII.

Firstly, some info on the ARC – production discontinued in 1996, when it retailed for around US$3000 – the MkIII was billed as a significant improvement over earlier versions – it is a hybrid design, with a single 6922 tube in the line stage, and another in the phono section – over the years I’ve compared it with some more recent ARC pre-amps and found it sweeter than some (SP16, LS22), and perhaps a little less transparent than others (LS15); having said that, I haven’t made direct comparisons with the current crop of much praised ARC products. It’s not particularly tube sensitive, but it currently runs an old Mullard E88CC, which seems a touch smoother than the others I’ve tried, namely: JAN Philips, Sovtek, and “orange shield” Amperex. I’m taking the ARC to be representative of a good “entry-level” high-end tube pre-amp.

The bottom line: not unexpectedly, the ARC added a touch of warmth, at the cost of rounding off some detail; in the upper frequencies this softening was very pleasing, while in the mid-range and upper bass it seemed unnecessary. However, the STI 500 retained a remarkably liquid and life-like presentation – the highs remained mellifluous; the extra information gave a precision to the placement of instruments, and made vivid the overall acoustic of the venue or studio. I don’t want to overstate the difference, as both set ups are very involving and listenable. However, if it comes down to cost, then the STI 500 provides almost all the sweetness, and actually bests the ARC in terms of retrieval of fine detail.

Here's a selection of some of the discs I directly compared...Perhaps for a string quartet, I'd still lean towards the euphony of the tube pre-amp, but it's a marginal call - Hadyn's Opus 64 No.2 quartet, played by the Quatuor Mosaiques, is a wonderful performance, with a good transfer, but the tone of the period instruments is a challenge as it verges towards the astringent - both W4S systems kept control and avoided harshness (as did the Jadis Orchestra Reference; the NAD C325BEE was unlistenable). Miles Davis Quintet, Live at the Plugged Nickel, has an atmospheric but not ideal acoustic, and here it was hard to pick between the two systems - the drive and energy of the quintet come through in either case, and the colour of Miles' trumpet is equally well served by either. A modern recording of a dense orchestral work, such as Mahler's Symphony No.1, Riccardo Chailly and the Concertgebouw, on Decca (recorded May 1995), shines a little more brightly on the STI 500, with greater resolution of inner detail and easier distinction between the string sections. Imperfectly recorded popular records, such as James Brown's "Hot Pants", or the remaster of the Beatles' white album, benefit from the tube input, sounding a little more "of a piece", less brittle; conversely, close to perfect technical recordings, such as Diane Krall's "Love scenes" or, in all its alleged "lo-fi" simplicity, Bonnie Prince Billy's "I see a Darkness" reveal more shades of detail and are rendered with a better sense of the instruments in an acoustic space through the STI 500.

The ICEpower sections are phenomenal. There are numerous professional reviews available, and I can only second their praise. In day to day listening the vast reserve of power means an incredible ease in listening to music with a wide dynamic range – there is no constriction or collapse when a piano solo explodes into a cascade of triple forte chords, nor when a slumbering orchestra erupts; a soprano or a counter-tenor are heard in all their power and clarity; Tony Williams’ cymbals hang in the air with a startling reality. Compared to the low-powered Jadis Orchestra Reference, the experience is more relaxed, and, surprisingly, just as true to tone, if not better. Bass reproduction is exemplary, and I’d say the STI 500 shades the ARC/ST1000 combination, thanks to a clarity and consequent speed of attack and release.

Of course it’s not fair to compare the W4S products with a modest NAD C325BEE – I have the latter as I was hoping it would do for a second system, mainly used for home theatre. The NAD has a nice pre section, and using this coupled to the ST1000 gives satisfying results – not a real-world combination, but it was interesting to hear how only a little detail was lost, and only the slightest coarseness gained. The power section did less well. In the end I found it not comparable – everything was compromised, although the bass output was remarkably powerful and lively, albeit a bit rough and crude; NAD like to claim their 50WPC is bigger than specs suggest, but I found it ran out of steam both with the Usher Be-718s and little Usher 520s – nor was I inclined to turn up the volume, since the tone and timbre were too coarse. If you own an NAD and are considering the step-up, you’re in for quite a shock. The STI 500 is better in every way – recorded music becomes comparable to a live event – and so it’s a pleasure to keep listening for hours.

With the STI 500 or the ARC/ST1000 a good source is essential. This was brought out by slipping in the Oppo BDP-83. Compared to the Audio Research CD1, the Oppo introduced a sharpness to the highs which was wearing. This was especially evident with violins, and with choral or operatic vocals. The ICEpower amplifiers resolve everything, so any added grain from the source is evident. Of course, this is all positive, as it means a great source sounds fantastic. Using the ARC CD1 with the NAD C325BEE brings only the slightest gain over the Oppo BDP-83 (it can't overcome the NAD's deficiencies) – with the W4S models, however, you hear the difference immediately, and the improvement is seductive.

Wyred4Sound warns that their amps take up to 300 hours to break-in. Take this warning seriously. The STI 500 has improved significantly over three months. For the purposes of this comparison, I pulled it from duty in the home theatre, listening to it afresh in the dedicated music room – when new it possessed all the clarity already mentioned, but also sounded a little thin and unconvincing; now it sounded full and true – to the point of approaching the richness of the Mullard E88CC equipped ARC. If you order an ICEpower amp, then keep it for a while - the difference between new and mature is not subtle. The W4S products seem to depreciate in value very slowly, so if you do decide to resell, it will be relatively painless.

I can’t be happier with the STI 500. I need two systems at present, so I’ll also be keeping the ARC/ST1000, but if I were coming in fresh, I’d opt for the STI, forsaking those honeyed tube harmonics for a few extra breaths of detail. Compared to the equivalent power amp, the ST 500, W4S are in effect asking $500 for a perfectly matched pre-amp, with five inputs, one being balanced, home theatre bypass capability, a well laid-out remote control, an incrementally dimmable display, and an incredibly precise volume control (for technical details see their website). The amp is also aesthetically inoffensive, modest in size, runs cool, and can be left on without detriment to reliability and with little waste of energy. I purchased direct from W4S and the staff were very friendly and helpful - shipping to Australia was very fast and inexpensive. Not simply a bargain, this is a great amp at any price.

Finally, a thought experiment - imagine if that $20,000 Gryphon, Krell, Musical Fidelity (etc.) suddenly enjoyed a RRP of $2,000 - would you rush out and exchange your amp for the newly affordable 50kg solid state behemoth? I think I wouldn't bother...

Associated gear
Usher Be-718s; REL Stampede; Audio Research Corporation CD1; Wire World Oasis 6 XLR interconnect; Audioquest Crystal speaker cables.

Similar products
Audio Research SP9MkIII/Wyred4Sound ST 1000; Jadis Orchestra Reference; NAD C325BEE
Thanks for the comments. Plato - I used the pre-amp section of the STI 500 coupled to the ST 1000 in order to compare the sound of the power amp sections. As mentioned, not much audible difference. After determining that the ICEpower units were largely indistinguishable, I then compared the SP9MKIII/ST 1000 against the STI 500, listening to the same tracks over a period of several hours. Re cables - W4S recommend balanced connections where possible - but I did try the RCA connections too with the ARC CD1 and STI 500 - frankly, the sound quality seemed very similar to me. All the best, Robert.
Any RFI? I had an early version of the NuForce class D integrated amp, and when I turned it on, no one in the building could play a radio. They fixed that via a redesign over time, but I always had the sense that class D amps are particularly prone to RFI.

Even after 13 years, this post remains timely and important. It is likely the only standing post that highlights the pre-amp difference between the STI500 (and STI1000) and ST1000 (and ST500) models of the W4S prior line. Thanks Audiogon for maintaining an amazing resource for us who continue to read, learn and listen!