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The Lejonklou Källa
Recently, while looking back over what I'd written for this magazine, I noticed that I mentioned "engagement" in nearly every piece. It makes sense. I believe the sole job of audio gear is to bring us closer to our favorite recordings and make us feel things. Musical engagement may sound frustratingly subjective, but in practice it's straightforward: If I find myself focusing on what the musicians are doing, engagement is happening; if I find myself thinking about the soundstage or the transient response, it isn't.

A component's ability to engage and its…

Big, bold, but not brutish
I began my evaluation listening closely to power tubes. The Bia 200 comes equipped with KT150s, but George supplied KT88s as well. I began with the latter. At the tube's only allowed bias setting—60Wpc—the Bia 200s with the JJ KT88s sounded laid-back, a bit slumber-toned, and easy on the ears. Lovely. Smoothness and textural sweetness were its strongest points.

The KT150s sounded entirely different, like a transparent membrane, now pulled tighter. No matter how demanding the music was, the KT150-equipped Bia 200s were happy to oblige. Moving up to…

Description: Class-A, stereo, dual-mono, push-pull, tubed power amplifier. Tube complement: (4) Tung-Sol KT150; (4) gold pin JJ ECC82/12AU7. Inputs: One pair XLR (balanced), one pair RCA (unbalanced). Outputs: two sets five-way speaker binding posts with 4, 8, and 16 ohm taps. Output impedance: 4 ohm tap, 4.0 ohms; 8 ohm tap, 7.6 ohms; 16 ohm tap, 12.3 ohms. Maximum power: 100Wpc into 8 ohms (20dBW) (high bias), 85Wpc (19.3dBW) (medium bias), and 60Wpc (17.8dBW) (low bias). Frequency response: 20Hz–30kHz, –3dB. Input impedance: 10k ohms balanced, 47k ohms single-…

Analog sources: Thorens TD 124 turntable/Jelco 350 S tonearm/EMT TSD 15N MC cartridge; Acoustic Signature Maximus NEO turntable/Acoustic Signature TA-1000 NEO tonearm/Luxman LMC-5 cartridge.
Digital sources: HoloAudio May DAC; Sonore opticalRendu; Roon Nucleus+; Small Green Computer power supply; TRENDnet switch; Apple iPad mini.
Preamplifiers: Shindo Labs Allegro (2), Sugden LA-4 line; Tavish Audio Design Adagio phono preamplifier.
Power amplifiers: Shindo Haut Brion, Pass Labs XA-25.
Loudspeakers: DeVore Fidelity Orangutan O/96, Spendor…

Sidebar 3: Measurements

I performed the measurements of the Zesto Bia 200 Select with my Audio Precision SYS2722 system. Following the instructions in the comprehensive manual, I carefully installed the small-signal tubes and the KT150 output tubes, the latter supplied as standard. With three auto bias settings for the KT150s, three output transformer taps—labeled 4 ohms, 8 ohms, and 16 ohms—and both single-ended and balanced inputs, this is a complicated amplifier. I performed a complete set of tests with the KT150s, using the single-ended inputs, all three bias settings, and all…

Thank you everyone at Stereophile for all their support. We are so pleased with Ken Micallef 's review and all his comments on the musical performance of our amp.

I would like to point out to your readers important conditions regarding John Atkinson's technical measurements on this amp. Tubes are the only active component in a tube amplifier, so all tube amplifier measurements are sensitive to the condition of the tubes. Tubes need to be tested separately before testing the unit. In this case, the amplifier was used to test the tubes, so the measurement…

I mentioned in my CanJam NYC intro that CanJams offer more than just networking and headphone auditions. (You can read part 2 here.) They are also good places, I noted, to access the house sound of virtually every good DAC and amplifier that will fit on a tabletop.

In my realm, there are two main types of audiophile sound systems: floorstanding and desk-sitting. Because, in contrast to floor systems, the user is positioned at arm's reach, desktop systems have 3D aesthetic that turns amplifiers and digital converters into artfully crafted tabletop architecture. The Woo…

It took Apple years to get halfway serious about music reproduction. The $2 trillion giant didn't offer lossless files via its Apple Music streaming service until mid-2021. Its early wired earphones…

One reason I green-lighted Rogier van Bakel's review of the Apple AirPod Pro 2 is that, while Bluetooth audio has a somewhat dubious past, its future seems promising (footnote 1). Bluetooth is a protocol that enables wireless audio and much else. Operating within the Bluetooth standard, or riding on top of it, are codecs for coding audio including SBC (the basic, default Bluetooth audio codec), AAC (preferred by Apple and used by YouTube), LDAC (from Sony), and several varieties of aptX (standard, HD, Adaptive, Lossless, and so on).

Sony and Qualcomm have…