I went from Class D to Luxman A/AB - And most of what you think is wrong

teo, what class D amps have you heard?

Not being familiar with the Luxman 507 ux  I decided to do a search (it's a integrated amp), but only found the latest version, the 507uxII. Positive Feedback reviewed it in September of 2018. This is what PF had to say
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 " L-507uXII is biased relatively richly into Class A operation, and indeed, while the amplifier never ran hot, it did get quite warm under normal operating conditions, so be advised that adequate ventilation is required. Having said that, the Luxman's sonics improved noticeably as it warmed up, and I typically left the amplifier powered up continuously to ensure optimum performance.

> The L-507uXII likewise reproduced the treble range with a level of transparency and refinement that was unique in my experience. Cymbals, bells and other high-frequency instruments were reproduced with a clarity and ease that was utterly beguiling.

>  The only potential limitation to the Luxman's performance was in relation to its ability to recreate a soundstage. This is not to say that the L-507uXII was was a slouch in the soundstaging department. Far from it. The Luxman threw a wide, deep soundstage, populated with palpable images. However, image layering and focus within that stage was not as finely-drawn and tactile as I've heard from competing amplifiers.   "

MSRP $6500. The MSRP of the 507 uX looked closer to $4700.
There are a lot of really good sounding current tech (not accounting for GaN) class D amps (no integrateds) in the ux price range to consider. The highs could be abated with input op-amps and/or cabling.

Now I realize teo-audio was talking about his observation after his class D Ice amp was powered down for a couple days with what input buffer?), but who needs to do that when they are so efficient?  Seems like a nothing burger to me

teo:

I understand your hypothesis and it is well articulated. The only issue I have is that I do not agree it is tightly intertwined with Class D operation. My AMR Phono stage is the best I’ve heard and it sounds great straight from standby mode but when that thing has been powered up for over 48 hours it is insane. Note that I said nothing about listening to it over this period of time, so it is not a brain-ear conditioning scenario. I’ve owned it long enough to know that is likes to be powered up for a while. It is why I power it up Thursday mornings as I head out the door and leave it powered until Sunday night. My Luxman EQ 500 could not care less ( if it could care :) about warm up, sounds the same from first hour to the last.

My Acoustic Reality Thaumaturges sound fantastic from power-up. They proved to me that class D can sound as good and in this case smoke many convential designs.

I have always believed garbage in garbage out. The power supply is the (in my opinion) most important thing. It is ultimately the power supply that is being modulated to create a facsimile of the original event.

I have three OTL’s, a S.E.T. (Reimyo PAT 777), a switching amp (mentioned above) and multiple push pull SS amps. I love them all and they all make music. Personally, nothing makes music like a well executed OTL but that’s for another thread :)

FYI, the retail price of the 507ux and ux ii in the US were identical until the latter was introduced.

The only difference in the two is a refinement in the feedback loop.
Luxman makes a lot of different models, so it is easy to confuse one for another, especially going by pics alone. :)

Best,
E

Let me first say I think Erik's post is great and I totally agree.

I have a Channel Island D200 fed by a Rogue Audio RP1 tube preamp into Harbeth Super HL5plus speakers. In moving to this system from a class A amplifier a couple of years ago I listened to a wide variety of electronics and speakers (to the point I’m sure vendors went "not you again" when I walked in. I was extremely impressed with the Benchmark, but it was out of price range. In one store I was able to compare what is now my system with a pricier but very good sounding all tube system and neither my wife nor I could here a major difference. I went with the class D in part because I decided I wanted to move away from hernia level components, although the price per pound of class D systems is much higher than class A solid state, let alone tubes.

One thing I find missing in this and almost every other discussion is the type of music being listened to. At audio shows I would bring some CD’s and a USB drive to try to listen to music I was familiar with. I listen primarily to classical music and two of the most revealing CDs were a recording of Mahler’s Fourth Symphony and Ravel’s Piano Concerto in G, pieces I am also familiar with from concerts. I found that systems that sounded good with the vendor’s selected music were frequently totally inadequate with mine. At a show, the best sound I heard with my music was the Benchmark with a speakers whose manufacturer I don’t recall.