Harman/Kardon PM635i Amplifier
The PM635i clearly takes over from the older PM635, though there are few visible differences between the two. Harman has sought to improve the '635 with binding posts rather than the tatty spring clip terminals fitted to the original model, though these do not include 4mm sockets. The styling of the PM635i is both luxurious and discrete - HK has abandoned all flashing lights while its dull gold lettering tastefully complements the satin black of the alloy fascia.
A small loudness button lurks to the right of the large rotary volume control which is joined by a series of six matching function knobs. Separate controls cater for input switching and full tape monitoring (the 635i has provision for two tape machines), the remainder facilitate bass, treble and balance adjustment in addition to headphone and A/B speaker selection. This last function is a trifle careless as the small ALPS switch carries the full power of the amp from the output zobel network to the binding posts at the rear. Goodness knows what non-linearities might be introduced as the switch contacts begin to deteriorate.
HK has also equipped its new baby amp with inputs for video, tuner, CD and phono (MM) sources, the line inputs being routed directly to the volume control. The disc stage is composed of discrete transistors and benefits from its own separately regulated power supply as does the final power amp section which utilises two pairs of Toshiba A1264N/C3181N bipolar transistors.
By popular concensus the moving magnet disc input was voted ahead of the standard line input which tended to sound dry and controlled but lacking in those emotive qualities of sparkle or 'magic'. CDs were slightly restricted in the dynamic sense as well as being a little reticent at high frequencies, a quality also linked to a reduction in stereo focus throughout the upper octaves. Stereo depth effects were better represented across the mid and upper bass but any sensation of deep, ambient low frequencies was missing.
By contrast the MM stage illicited a stronger emotional reaction; vocals were clearly delineated even if the stereo images of accompanying guitars and percussion were somewhat less distinct. The overall balance was warmer than the line input with a less immediate though (to quote one listener) more fluid and 'authentic' presentation. I also feel the disc input offers a very enjoyable and fairly detailed sound though its flattening of deptli perspectives could stand some improvement.
Having frozen the price of the PM635 amplifier HK should at least be commended on the build quality and perceived value of the product. Furthermore, a reappraisal of its unpleasant distortion mechanisms might reap further rewards. Better suited to the sweeter sounding CD players currently available, the Harman/Kardon PM635i nevertheless comfortably achieves a recommended status.