Just bought one of these, mainly because I already had the M400 which I am impressed with. Bought direct from HiFi-Express and they paid the VAT (UK).
I had read this review and others, and the whine/noise reported did concern me. I was coming from a DEQX/Temple Audio Supercharged Monoblocks.
Unit arrived a week later, and as soon as I plugged it in, I packed it away to return. The whine was so loud I could hear it in the hallway!
I logged onto the returns page, and HiFi Express had a 35% restocking fee. Ugh...........
Ok.....set her up again and started listening through the whine. Using the balanced connectors from the M400, the sound was immediately impressive.....clean and dynamic.
Having read about the heating issue, I set about finding the fan menu to reduce from 65C to 48C. Hmm, it was already set to 45C. With continuous operation, the temperature never rose above 42C, which is perfectly acceptable to me. Even my Temples get pretty hot in operation.
......just the whine....I could not live with this. I Googled coil whine and many people said it reduces on its own. To get to the point, in my case, this turned out to be true! I have had the unit a week, and now the coil is below fan noise level which I can live with. It actually started to reduce in volume within a couple of hours.
Playing around with the presets, I like the 'clear' setting. Need to be a bit careful because the Bass, Middle & Treble controls work with the presets, and I thought there was an issue with my speakers when the mids were missing. I subsequently discovered the mids were set to -4db! This is a very versatile amp.
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So now, the amp is a keeper. As she opens up, things are sounding better and better. The detail she retrieves has startled me on a few occasions
and the old Mono set up sounds rather boring!