The $450 Carat Topaz is an impressive device that offers performance on the scale of larger, notably more expensive units. In many ways it remains a hard unit for me to nail down, as it is too small to be "full sized," but too large (and AC dependent) to be truly portable. That said, it performs an awful lot like a full-sized system, and at the end of the day that's what matters most.
The Topaz drove all of my cans admirably. The 701s sounded very good, the Senn 600s sounded great, and my Grado RS-1s sounded fantastic. The Topaz and RS-1s seem to make a very synergistic pair, with the combo offering up crystal-clear voices (without ever sounding digitally edgy), excellent instrument separation, and something I guess I would best describe as a forceful drive. All in all, I think you can safely pair the Topaz with any of these headphones, but listening via the RS-1 left me with the impression that there was more there, there. After listening to a series of songs with all three sets of cans, I settled on using the RS-1s for the remainder of my time with the unit.
Next, I spent some time comparing the Topaz with the other DAC/Amps I had on hand, using the RS-1s. My main rig consists of a PS Audio Digital Link III paired with a Headroom Desktop Millett Hybrid Amp. Conservatively--and not counting interconnects, upgraded power cords, and the Millett being out of production--that rig today would cost you at least $1,300 new. For our purposes, let's say that setup ranks a 10 to my ears (translation: I really, really love the robust, clean, and smooth sound this combination produces).
On that scale, I put the Topaz at a 7.5. Not bad for a $450 product. Further reference: I'd put the Headroom '06 MicroStack (DAC+amp) at roughly 6.5 on that same scale, and the Pico DAC/Amp at 6.
Now before all the Pico lovers in particular start cursing my name, I'd like to point out that I think the Pico is a marvel of a device. Amazing sound quality, and the only truly portable device among those listed here (I consider the MicroStack a luggable). The Topaz is much larger than the Pico, and the designers clearly used that additional space in the service of better sound quality.
After a fair amount of listening to all three devices, and then using the Topaz DAC to drive first the Pico's Amp and then the Micro Amp, I came to this realization: The magic here is the DAC. It offers a level of clarity and authority that's nearly in the same league as the PS Audio III. Not quite there, but closer then I guess I'd like to admit.
Anyway, I think it's worth noting that the Topaz upsamples everything to 24/192. In my experience, that amount of upsampling can make music sound thin and lifeless. In fact, while my PS Audio can also upsample to 24/192, about 99.9% of the time I set it to 24/96 for a sound I find more pleasing. However, the Topaz clearly has the 24/192 dialed in well, as all of the quality recordings I listened to sounded good.
Moving on to a few hardware pros and cons:
Pros:
*I very much like that the unit uses a full-sized headphone jack instead of a mini.
*The pre-amp capabilities are a major plus, and make the unit a shoe-in for desktop service.
*Build quality seems top notch, and fit and finish is good.
*It's nice to have both USB and a full-size optical input options.
Cons:
*I wish the USB input supported native 24/96 files (The Topaz USB downsamples these to 16/48). Alas, it seems that this capability is reserved for only higher-end products (such as Benchmark's $1300 DAC1 USB) or lower-end products (such as M-Audio's $99 Transit). Can anyone explain this phenomenon to me?
*A gain switch would be nice.
*The topaz-colored LED up front is way too bright (yes, nitpicking, but…my eyes…it burns!!!)
All in all, I found the Topaz to be a fantastic "little" unit, and one that I could recommend to anyone who's looking for a very solid, non-portable DAC/Amp combo.
Like Deadie, I'll finish up my review with a few words about the Spotlight USB cable. I contacted Craig at Whiplash to get a few more details, and found out the unit is completely handmade. It features "Cryo'd OFC single conductors with extra damping and a high end USB connector" and sells for $187.
Honestly, the thing I noticed most about the cable was the connector, which seemed to better grip the USB jacks of both the Topaz and PS Audio III DAC then the standard cable that ships with the Topaz. Beyond that, it's a nice looking cable, but to my ears I could not hear any difference. Maybe I'm too skeptical to let myself hear a difference, or maybe there really isn't one.
I've recently begun to spend a little money on new interconnects and power cables for my main rig, so I clearly see a value to these types of upgrades. At this point, however, I haven't seen--nor heard with my own ears--evidence to convince me to spend $187 (or more) for a USB cable.
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