Tube Power Amp Reviews

My listening room measures 26' long, 13' wide, with a 12' semi-cathedral ceiling. An 8' high by 4' wide doorway at the back of the room opens into a kitchen, adding an additional 25' by 15' area. I also used a second listening room, 17' by 10', to audition the MA50s.

I compared the Woodsides with a Mark Levinson No.27.5. Additional gain-matched listening tests were conducted with a Krell KSA-250. Because its power ratings are twice that of the Woodsides, sonic comparisons with the Mark Levinson focused on low-frequency extension, imaging, soundstage presentation, and instrumental timbre. Each amp had its own strengths: vividness, speed, and bass definition (Mark Levinson No.27.5), and bass definition and depth of soundstage (Krell KSA-250).

All amplifiers were set up in a basement room below my listening room on a solid workbench, with easy access to AC outlets with 200A service. This allowed me to switch rapidly between the Woodside, Mark Levinson, and Krell amplifiers, but it also required a 45' run of AudioQuest Topaz single-ended interconnect between preamplifiers—the Krell KBL, the Woodside SC-26 tube unit, and a Classé DR-6 Mk.II with an internal moving-coil module—and the amplifiers. Care had to be taken positioning this lengthy 45' interconnect, for the Woodsides easily picked up hum. Floating the AC line cord with a "cheater" often helped eliminate this hum, but not always.

CDs were played on a Krell MD-1 turntable driving a Krell SBP-32X digital audio converter. A Day-Sequerra FM Reference tuner and a Quad FM-66 FM tuner provided music from WQXR, our local New York classical station. Levinson HF-10C cable and Cogelco Yellow balanced lines connected line-level sources to the preamplifier. Vinyl records were played on a Linn Sondek LP12 turntable with a Lingo Mod, an Ittok arm, and a Spectral moving-coil cartridge.

Loudspeakers used with the MA50s included electrostatics (Quad ESL-63s on Arcici stands), full-range dynamic loudspeakers (Snell B minors), and several minimonitors (Chario Academy Ones on sand-filled Sumiko Franklin and Lowell Stands; Totem Model 1s on sand-filled Target R-1 stands). Speaker cable was bi-wired Sumiko OCOS cable.

Each speaker was auditioned separately in the listening room and placed at the same location: 4' from each sidewall and 3' from the back. I also listened from two positions: For nearfield, I set up my listening position 8' from the speakers; I also listened from my favorite spot, which is 18' away.—Larry Greenhill