ICE amps need cooling?

Muralman - I don't know how many times I have to repeat that - CLASS D IS SWITCHING POWER SUPPLY. Switching itself does not make class D or SMPS digital. Both of them are exactly the same thing.

There is very little noise in properly designed SMPS (my Rowland 102 has 110dB S/N).
Noise is at non audible frequency
This frequency is easy to filter out (that's why Rowland uses it in preamps instead of linear

AS for linear power supply - it is not class A. Class A is an active regulated supply while linear PS in neither active nor regulated (line and load). It produces 120Hz ripple in-spite of huge number of capacitors. There are good and bad realization of each technology but the fact is that linear one is unregulated.

Kijanki, B&O would find your notion the modulation process is the same as the switching power supply unit insulting, or more likely, hilarious.

Henry Ho, an advanced electronics engineer is quite capable of creating a power supply that has no measurable ripple or other distortions. The 250A module is built to accept any power supply. My sound is proof enough.

By the way, take a look at the graphs provided by B&O. They show a distinct advantage of the A250 over the ASP250.

Muralman1 - yes it is pretty much the same. I have no idea why you call switching power supplies digital and amplifier analog. Both of them are analog (no discrete values) and both operate with PWM and feedbacks. Modulation process might be different but purpose of power supply is different - input value is constant and feedback keeps output constant. The issue that you raised was noise. Since both operate at the same principle (pulse width modulation) and the same power - noise product of both is the same and very easy to filter out.

Icepower doesn't even bother to filter amplifier's switching noise completely and leaves about 1% on speaker wires. This noise is not audible and can modulate the sound only on non-linear element. Tweeter is potentially one but only if membrane moves (it cannot at such high frequencies). It cannot radiate because it needs hundreds of feet of wire to create 1/4 wave antenna.

There is quite few amps built with 1000ASP module that includes built in SMPS (40 Amperes) and very good reviews.

Let me repeat again - SMPS are regulated (line and load) and can deliver a lot of current - each of 1000ASP modules have its own 40A SMPS.

B&O guys are audio freaks and would never design substandard SMPS to their Icepower modules. I would be happy to discuss it with them if they would find my statements "insulting" or "hilarious". I design electronics (including SMPS) and am familiar with Karsten Nielsen doctorate work.

As for Henry Ho - he might get very low ripple by using a lot of capacitors but you're paying for that and power supply is still completely unregulated same way it was designed more than 50 years ago. Class D was invented during demonstration of response of SMPS. Engineers claimed that SMPS was so fast that it could even play music. Since then SMPS got highly specialized as well as class D. Requirements are different since SMPS is unidirectional and holds constant output voltage but they both got quite sophisticated with a lot of high quality ICs released in recent years.

B&O developed ICEPower technology with much research and help from their government. B&O uses the units in their mass market systems and also sells them to the likes of Rowland, Spectron, Bel Canto, etc. Some people just stick them into folded metal boxes, but those mentioned add proprietery improvements to integrate them into their own designs.

Yes, switching and digital are two different things. Too bad they didn't call it Class E instead. I think that the "D" confuses lots of people, even though it holds no significance other than being the next letter in the alphabet after A, B and C.

Dave

Just for the record. Current generation of Spectron amplifiers do not use switching power supplies. I will not go into reasons, sorry.