Pre/Power Amplifiers

At last, Levinson’s flagship No53 monoblock amplifiers [see HFN Jan ’11] now have a Reference-status preamplifier with which they may be rightly partnered. The No52 is a two-chassis component designed with meticulous attention to detail both in its topology and in features that offer comprehensive system configurability. The rationale of this approach is to isolate the pure analogue audio circuitry from any possible source of pollution: it physically separates the power supply and microprocessor-driven controls from the audio electronics contained in the larger chassis. Volume control is via a precision ladder resistor network with fine gain adjustment in 0.

User-friendly features are a major aspect of the current VTL Signature Series, including the power amp reviewed here. Based on four 6550 output tubes per channel, it has newly-designed output transformers, a larger power supply, and the Signature Series control electronics. When running, the tubes can be seen discreetly glowing through the smoked glass front window. (Our sample was fitted with KT88s, an option that adds £200 to the price.

Each of these three units – preamplifier, two-channel power amp and a power supply to ‘beef up’ the power amp’s performance – is housed in an all-aluminium chassis identical in size and appearance. Pre and power amp are ‘double mono’, the left and right channels both electrically and mechanically separated, with power supply sections, audio circuits and control electronics all in shielded chambers. The new P3000HV preamplifier has a comprehensive functionality that includes an analogue tone processor module to provide bass/treble adjustment, a user-variable ‘loudness’ control to suit your loudspeakers’ sensitivity, and parametric equalisers for tuning your speakers’ bass performance to your listening room. Illuminated touch-sensitive controls allow access to the preamp’s configuration menu, and a headphone amp is built in as well.

Furutech’s Alpha Design Lab range includes cables, headphones and earphones, a portable headphone amplifier and stylish system equivalents of the ADL X1 here. This appears to be a portable miniature music centre, offering USB and iDevice functionality, plus a built-in rechargeable battery giving around five hours of operation. Six top-mounted LEDs display sampling frequency, and there’s a front fascia volume control – which sadly proved just a little too easy to accidentally move when out and about. Those on the Number 41 bus will doubtless prefer the ergonomic simplicity of, say, an Arcam rPAC or Cambridge Audio DacMagic XS, which are truly portable devices.

McIntosh’s original MC275 featured as an ‘Audio Milestone’ [HFN Dec ’10], but what’s reviewed here is the current production version of this most famous power amplifier. It’s the same as the 2011 Anniversary Edition but with stainless steel rather than a gold chassis. Its most spectacular outward feature, described in staid McIntosh tech-speak as ‘small tube illumination for amplifier status operation’, comprises LEDs indicating status or output tube failure. This is a part of a protection circuit system which will also shut the amp down if speaker wires are shorted or there is a gross impedance mismatch.

On seeing Siltech’s pre/power combo you might think it incorporates a separate power supply. In fact, this unusual design splits the power amplifier into separate interstage (voltage gain) and current amplifier sections. The combo’s C1 tube preamplifier (pictured) features a rechargeable battery power supply as does the V1 voltage stage of the two-box power amplifier. Of course, running the complete V1/P1 amplifier from a battery would be wholly impractical, so the P1 is mains powered.