Did not get my Accuphase P4600 until June 3 as it missed the April shipment. Although It sounded really nice out of the box it took a couple months to settle in and open up. I’d guess 300 hours. Now it’s just wonderful. Open, clear with a very deep and wide soundstage. Imagining in particular is excellent. Each instrument is clearly defined in space and voices are lifelike. Speakers disappear and the image is set back just behind the speaker plane. I do not notice any frequency anomalies. Everything is smooth and even. Bass is very good. Something I thought might be an issue. Don’t even use my sub. As a Classical music listener strings are silken and brass is never sharp or piercing. I’d describe it as just slightly on the warm side of neutral. I can and have listened for hours sometimes up to 8 without any fatigue. I also listen to Jazz and Pop with the same result. Now it does let me know when a recording is not good but never in a way that makes them unlistenable.
I seem to have more than enough power (150W per channel@8Ohms) as the meters never register more than 1 watt. I typically listen at around 65-70db.
It’s beautifully made, a pleasure to look at and listen to. A noticeable upgrade over my Benchmark. So I’m very satisfied with this amp.