Solid State Preamp Reviews

Because first impressions can be misleading, I believe that audio equipment should be auditioned over a long period of time: the Bryston BP-25MC preamplifier was used in my listening system for nine months before I began writing this review. The BP-25MC was compared with the discontinued Mark Levinson ML-7A and its moving-magnet L2 phono option (set for 44dB gain and 50k ohms input impedance), with a Duntech/Audio Standards MX-10 head amp for my system's low-output Spectral moving-coil cartridge. Analog interconnects included AudioQuest LiveWire Topaz interconnects and Krell Cogelco balanced leads.

Listening tests were carried out in two rooms. The first, my main listening area, is the most spacious, having an estimated volume of 5500ft³ and an effective room length of 51'. The main listening area is 26' long by 13' wide by 12' high, with an 8' by 4' doorway at the back of the room opening into a 25' by 15' kitchen. With only a single area rug, this space is a "live" listening environment. (This large room's exact dimensions, construction, contents, listening positions, rugs, windows, and bass modes were described in Vol.15 No.3, p.181.)

For the preamplifier listening sessions, a single amplifier/loudspeaker setup was selected consisting of Snell Reference Type As with a pair of Bryston 7B-STs driving the Towers, and a now-discontinued Krell KSA-250 driving the SUB-1800 subwoofers. The two preamplifiers were linked to the Snell EC-200 Electronic Crossover via a pair of AudioQuest Topaz single-ended interconnects. Single-ended Randall Research interconnects were used from the crossover to the 7B-ST and Krell KSA-250 power amplifiers.

Other associated equipment used in the main listening room included a Day-Sequerra FM Reference tuner, a Rotel RHT-10 FM tuner, and a Linn Sondek LP12 turntable with Lingo power supply, Ittok arm, and Spectral moving-coil cartridge. CDs were played on a Krell MD-1 turntable driving an Audio Alchemy DTI jitter attenuator using a 75 ohm Silver Starlight digital coaxial cable. This unit fed either an Adcom GDA-700 D/A processor or an Audio Alchemy DDE v3.0 HDCD over its I²S bus. This converter was fitted with an RW-1 Remote Wand One.—Larry Greenhill