I installed a Leben CS-600 integrated amp today. It's driving my long-time favorite Von Schweikert VR4 Gen III HSE loudspeakers. The CS-600 is powered by an Empirical Audio Power Cord connected to a Hydra 2 conditioner which is fed by a Purist Audio Dominus Ferrox power cord from a 20a dedicated circuit. The source is a Modwright Sony 999ES Signature Platinum edition with tube rectified power supply. Interconnects are Stereovox HDSE. I'd have preferred to use my Purist Audio Aqueous Anniversary or Venustas interconnects, but they are slightly too short for the temporary audition position of the Leben.
The first impression of the Leben is it's fairly compact size, especially compared to the amplifier it replaced. However, it's heavy! 60 lbs, and a good portion of that weight attributable to four sizable transformers. I off took the ventilated, beautifully-powder-coated top to swap tubes, and the top alone must weight 3 or 4 pounds. No lightweight aluminum here.
The power tubes can be a wide variety of types. Stock tubes are Sovtek 6L6GC producing 30 wpc. My demo unit was also furnished with a matched quad of SED Winged "C" EL34 for tube rolling (28 wpc). Other power tubes that can be used are 350B, KT88, and 6550A. The circuit is self biasing. It's a pleasure to know replacing four power tubes will cost no more than about $200 for a set of premium RCA 6L6GC, or $80 for a matched quad of SED EL34.
Input/Driver tubes are 6CS7. Again, replacing these tubes with NOS RCA, Sylvania or GE vintage tubes runs about $5/ea.
One damper tube (I'm assuming this is a rectifier) is a 6CJ3. About $5 for a vintage NOS GE 6CJ3.
Five sets of RCA inputs, plus a tape loop, and a set of RCA inputs for a preamp if one chooses to use the CS-600 as an amplifier only. Or, the preamp inputs can be used as a direct input for a source with enough gain to not require a preamp (like my Wright Sound WPP200C phono preamp). When the direct connection is selected, the volume control knob functions, but the rest of the CS-600 features like balance control, stereo/mono, and bass boost are bypassed.
The Leben also has a rotary switch that changes the output of the speaker taps between 4, 6, 8 and 16 ohms. Nice.
Once connected, I was stunned at the silence of the amp. I mean dead, stone-cold silence with my ear to the tweeter. I have never owned any tube gear that was this quiet.
Thus far, the amp has no problem driving the VR4 loudspeakers (89db/1w/1m, 6 ohm nominal, 3 ohm minimum). I can't say it will crank as loudly without distortion as my Moscode 401HR, but the times I did that were rare, and resulted in volumes of 110+ db in a 16x19 foot room. Fun to do on occasion, but not normal listening for me. Without using the decibel meter, I'd guess my listening this evening was in a decibel range in the high 80s to low 90s. I listen nearfield...about 8.5 feet from the drivers.
This should be a fun two weeks.
