my receiver also heats up even when idle, my previous marantz also heats up when idle..only when you start watching or listening to music does the heat really pick up..which is due to both having high current designs. what i'm just pointing out is that the amps in the h/k receiver are not pure class A, it may be class A to a certain degree but switches to B to generate more power, amps that are class A/B give more power to speakers running in class B rather than pure class A. I'm sure when your yamaha amp (which is a class A/B amp) is using class A it produces lesser but much cleaner, clearer power. There is this amp from pioneer which was from the late 70's that can operate on class A and AB. On class A it can give 20 watts per channel, but on B it can go up to 70, siyempre mas maganda yung sound pag class A even if its "lesser"
Hk has an integrated amp (HK 670) that gives 70w x 2 and is quite compact. It also generates a lot of heat similar to its receivers but its not running on pure class A its either A/B or B, an amplifier running on pure class A giving 70 watts per channel will be twice or maybe thrice the size.
As for the hk 5550 it should come with a fan because the heat generated from 7 amps running at the same time may not be compensated by heatsinks alone (it might be possible but the heatsinks would be quite big, the casing will not be compact anymore), another thing baka masira kaagad yung other components sa receiver like the processor, DACs etc.
I am not sure if my NAD receiver runs on class A/B or B but it also generates a lot of heat, you should feel it after watching the Matrix
that's where the fan kicks in to sort of cool it down because the other components might break down due to the heat, na complaint ng iba kasi in some medyo maingay yung fan. NAD is also conservative in its figures like harman and what its states for specs are just the minimum power, it also runs on 100 watts per channel continuous in stereo mode with dynamic power to spare. Please, NAD should not be put in the same league as some japanese companies entry level receivers.
I also had a hk receiver previously so I know how it generates heat and how it sounds, yun nga ang napapansin sa bahay e, the receivers that I buy can double as heaters...buti di ko pa inuumpisahan audio setup ko hehehe.
Basically they are similar in thinking on the way amps should work, give more current to speakers, hence the mammoth power consumption and high current design. because its the sound that matters ;DLike I said I don't think the amps in the receivers run in pure Class A but that does not mean that it sounds bad which is what I keep reiterating. Cheers!
