Responses from ohlala

LS50 + Sub Or Floorstander?
You can be successful either way. I think a main goal with adding a subwoofer is to even out the bass response. To do this you have to solve the room modes and the bass response of the the LS50 at the same time. There are additional tools like EQ,... 
Balanced vs. Single Ended Interconnects
My interpretation of an old almarg post is that some noise rejection may occur connecting XLR with just one of the units being balanced, so I gave it a try.   
New transport or repair CD player
I am all about maximizing the lifespan of gear, but based on my experience using a Cary 303 as a transport, I would audition a new one. The change from the 303 to a server/built-in renderer was a decrease in that digital-type distortion.  
Balanced vs. Single Ended Interconnects
I tried XLR mogami vs Purist Proteus RCA (5m) from an unbalanced crossover or preamp to a fully differential amp. The Purist sounded like Purist and the XLRs sounded more distorted, which was the least surprising outcome.   
Help finding a subwoofer
An active crossover is there is to solve an issue, but you do not yet know if you have that issue or if you even care. REL subs are actually fairly limited in features.  I wish I could easily show pics of my best REL vs best JL Audio waterfall gra... 
Raising Subs?
I have tried this with one and two subs to reduce a vertical room mode. It partially worked, but as usual other frequencies that I worked hard at to get just so were compromised.   
Looking for a streamer/DAC
According to Brian of Bricasti the internal network player of their DACs performs better than the outboard streamers, citing a I2S > AES > USB.   
Diagonal seating?
I have been down this road where I thought imaging shift was a result issues like the room, the electronics or my ears, but symmetric speaker placement along the center line of the room, mirrored toe-in and equal distance of the speakers to the li... 
Positioning B&W 802’s with spikes in hardwood?
If it we're me, I would put mark the placement of the speakers by way of blue tape, measurement from side wall, whatever..., place the spikes, tip the speakers back upon metal discs made for spikes. You can move the speakers some this way and can ... 
B&W 705 Signature Feedback ?
Don't concern yourself with the room size. I would also suggest listening to other speakers as I think the N805 is a more natural sounding speaker than D4. Best of luck.   
Pair of Rel S510’s or Carbon Special’s?
I have been there and was an owner of the S510 and now JL. I have a few thoughts about your situation based on my experience: 1) The S510s are too small for a large room with large speakers. 2) I would try the DSP function to see if you can get ... 
Music Metre Signature Audio cables
I have owned a pair of silvers for the past twenty years or so, if that means anything to you. Took them out of the drawer last year to connect a crossover.   
Moved from medium attic like room to larger room, everything is too bright
I also have an echo issue. The cheap and easy way to really tell is how easy it is to understand other people talking in that room, especially multiple people at a time, or the hand clap as suggested above. It can also be measured with microphones... 
Mark levinson 532h and 531h
I own the 532H. It was annoying with high level connection to subwoofers, always popping and going in to protection mode. Other than that I appreciate the woofer control, the large & slightly laid back soundstage and very even-sounding bandwid... 
Vandersteen Forum
I once criticized the frequency response of a past version of a Vandersteen model. Someone called dad to tell on me, which was weird. Poor Richard.