Anyone experienced the Luxman MQ-300 or/and The Air Tight ATM-300R?

Hi h_bomb,
You’ve confirmed something I’ve written numerous times on this forum, you just have to audition audio components and listen for yourself. What satisfies one listener may not satisfy another. Simply too many personal taste/preference factors involved. I’m glad for you that the Luxman 300b SET and your Devore speakers have resulted in such a successful pairing for your needs and desires. Nothing ventured nothing gained.

"Little Sophia"  300b SET vs the Luxman SET, no doubt that power supplies and output  transformers differences are a major factor favoring the Luxman amplifier. The Luxman is probably 2 or 2.5x heavier.
Charles 

Thanks Charles, you are totally right about trying in your own set-up . What is really a surprise for me is that it is actually much more powerful than I thought. 

h_bomb,
I can understand your preference for the 300b compared to the KT 88 amp you currently have. The KT 88 is a very good sounding tube if well implemented. However IMO a well implemented 300b is quite formidable and alluring 😊. I was a happy owner of a KT 88/6550 push pull amplifier. Once I got my 300b SET thers was no going back. That was 10 years ago. I believe that you will enjoy your Luxman SET amplifier for many years.
Charles

There’s no replacement for displacement they say. The MQ-300 has transformers that weigh a ton in comparison. It’s a wonderfully beefy 8wpc. I know from experience. I had no doubt it would work in his situation. 
I’m so happy he is experiencing that awesome amp. 
Enjoy it in great health!

I actually think they are 2 superb superbs amplifiers and I might keep both. The 300 though has a built I had never seen before though. It is really a statement product.