Theta Digital Intrepid 5-channel power amplifier Page 2

Two + Two = Four
Well, if two 100W channels ain't quite enough, the Intrepid has more. Because the Sonic Frontiers Line-3 preamp has duplicate pairs of XLR and RCA outputs, I next undertook to biamplify the speakers by using four of the Intrepid's five channels. I heard no significant changes in balance between XLR and RCA, but now, when a low-frequency surge came by, there was some heft to it.

Running back through my torture discs, I confirmed that, while meeting the power requirements of the B&W S800s at full cry was simply asking too much of even a well-behaved 100Wpc amp, now, with biamped Intrepid providing 200Wpc, power per se was no longer an issue. All of the lovely smoothness and transparency was preserved with the four Intrepid channels in operation, but now it was extended into the bass. Even so, the Intrepid couldn't get the S800s or the Studios to rock the room—as they did with Classé's CAM-350 monster monoblocks, which continually goaded me to crank them higher.

Now, any good high-end amp—eg, any of the ones I've mentioned—has low distortion and a smooth measured response over the audible frequencies, and sufficient power reserves over that range so as not to be stressed at normal domestic listening levels. Nonetheless, each amp gives an immediate impression as the listener latches on to one or another aspect of its performance. In the Intrepid's case, it was the sweet, clear, grain-free sound from the midrange up through the extreme treble, which reveals human and instrumental voices with delectable precision and presence.

While at the 2002 CES I was given an advance pressing of the forthcoming Mobile Fidelity SACD release of Patricia Barber's Modern Cool. Its superiority over the regular CD (Premonition/Blue Note 5 21811 2), or the SACD's own CD layer, is remarkable. The accompanying instruments are even clearer, with greater kick, but it was the delineation of female voices that fascinated. With the S800s or the Studios, the Intrepid continually gripped me with its astoundingly natural reproduction of Barber's voice. Of the other amps on hand, good and pricey as they were, only the SF Power-3 could equal this aspect of the Theta's performance.

However, through my extended and enjoyable listening sessions, I often wondered why I was not paying any attention to the rest of the music—in particular, the lower frequencies. The Intrepid could generate substantial bass and provide fullness in male voices and lower strings, but that seemed not to be its immediate and defining character; the lovely midrange and treble were. Is this analogous to being so infatuated by one aspect of a person that one ignores everything else? Was I simply smitten?

A Drive in the Country
Aside from the heavy lifting, I figured it would be a piece of cake to swap the Intrepid for the Bryston 9B-THX in my multichannel system, now that I had Harmonic Technology's nifty, color-coded, RCA-terminated cables. Well, the connections were easy, but all I got when I turned on the amp was a few seconds of loud buzz followed by a lot of hum. I assumed that the culprit was a ground loop from the cable-TV input, but the usually reliable Mondial Magic Splitter couldn't banish the noise.

I went back, read Theta's manual, and found multiple admonitions to provide the Intrepid with a good ground. Most of my country house was built more than a century ago, and the electrical outlets in the music room have lousy ground connections. A good one was 25' away, in our modern laundry room, newly plumbed and wired to code, so, with little thought to its effect on the décor, I did the rest of my listening with a bright yellow 20A cable laid across the carpet.

This was not quite enough for the Sony TA-P9000ES preamplifier. Even with the system now properly grounded, there were a few anxious moments. The Sony had always buzzed lightly for a few seconds at turn-on, even with the Bryston amp, but the only way I could get the hum to be bearable with the Theta was to disconnect everything from the Sony's pass-through inputs when using the active ones.

Who's at fault? Everyone. First of all, the Sony TA-P9000ES seems to be somewhat vulnerable to induced noise from sources inside the chassis and without. Second, the Intrepid has both XLR and RCA inputs, but lacks a switch or jumper for single-ended use. I suspect that the single-ended RCA cables are terminated across the differential inputs; while this would not be a problem with most sources, the Intrepid can amplify the hum and noise from those that are less well-behaved (like the Sony). Third, since the only decent ground is in the next room, I face the prospect of new wiring if, in the future, I desire to cast the first stone.

Theta Digital
5330 Derry Avenue, Suite R
Agoura Hills, CA 91301
(818) 597-9195