I’ve owned both the integrateds and the separates, in my opinion the preamp section of the integrated amp is not up to par with the amplifier. To do justice to the amplifier you should really get the matching preamp, which is fully balanced and differential. The integrated just has single ended outputs. I currently have a 590ax II and have tried its preamp output with some other amplifiers, and it isn’t that great compared to standalone preamps.
Luxman Preamps
My Luxman M-10X power amp and Blade One Meta orders supposed to come in this month(I ordered them back in Aug). I'm having a hard time deciding what preamp to run the M-10X with. Right now, I have a Luxman 595ASE which I was going to use the front end as the M-10X preamp. However, the 595ASE is a class A integrate and draws full power as soon as it powered up. And it gets hot. So It may not be the best component to use as a preamp.
The best obvious choice would be the current C-900U but the problem I have with it is that a replacement C-10X is on the horizon for next year. However, it will cost quite a bit of money. Since my listening setting is "Line Straight" and do not need any of the tone control from the preamp, does it matter if I'm using C-900U or C-10X or any other older pream with line straight?
Are all "line straight" from Luxman preamps the same? If this is the case, perhaps I can get a 507z, 509x, or future 509z integrate and use it as the front end of the M-10X power amp. The only thing I see here is that the integrates don't have a balance pre-out option like a dedicated preamp.