Hi Frenche,
I haven't listened to H/K's "digital-path" line, so I just don't know. There are unquestionable advantages to digital amplifiers if the design is done right (a big IF...). First, they are much lighter and smaller and much more efficient than analog power amps. For instance, the Axiom's unique digital amplifier design for the EP500 and EP600 subs (it has an analog power supply, unlike many digital amplifers) has more than 90% efficiency vs. about 50% or less for a conventional ananlog solid-state amplifier. So you can get a lot of power with much less wasted energy in heat, and you don't have to include elaborate heavy heat sinks and cooling fans because digital amplifiers are barely warm, even at very high output.
But, because the switching frequencies of digital amplifiers are very high-frequency, you have to be very careful about preventing a digital amplifier from operating like a small radio transmitter, causing RF interference in nearby equipment.
Digital amplifier technology isn't that new. I recall reviewing a very small, powerful, lightweight car-audio digital amplifier about the size of a hard-cover book, which Infinity introduced back in the 1980s. Even when it was isolated in the trunk of a car, it still produced interference with AM and FM reception in the car's in-dash tuner. But shielding designs have greatly improved since then. Another potential liability, like any digital device, is preventing clipping. A digital amp will clip instantly in very nasty fashion if driven past its output limit. But there are ways of avoiding this.
Another advantage is a digital amplifier's ability to drive very low impedances-- to 1 ohm or less-- with none of the problems of analog amplifiers. Axiom's EP500 and EP600 subwoofer digital power amp handles the very low impedance of its 3-inch dual-voice-coil driver with no problems.
I will be doing some listening tests in upcoming months to a digital amplifier intended for full-range reproduction, so in time I shall report.
Regards,
