Audio Research VT100 MK1 and LS15 HELP!!!


I recently bought this set VT100MK1 and preamp LS15 and while I was at this seller house he demonstrated the sound from his online Tidal on TV connect optical to the DAC Luxman DA - 06 then this go to the preamp LS15 and out into the VT100. This set up sounds amazing at his house. However, when I came home play CD from the Sony X1100ES Blu-ray player RCA output into the LS15 and out to the VT100 and it sound horrible - no bass at all in any type of music.  The sound sometime muffle and not clear and most importantly the bass missing tremendously. Im using a pair of KEF R900 Speakers. What is wrong here? can anyone help me correct the sounds? it is because I didn’t have the Luxman DA - 06 DAC? or it is because I don’t have those fancy hundred - thousands of dollars cable?  or the CD source is playin at 41khz /16 bit not high enough signal?  

This is my first system and I don’t know why I can’t get that high fidelity sound from the ARC equipments.  I'm waiting for the Audioengine B1 to arrive so I can stream Spotify into the LS15.   What is wrong with my set up?  Thank you in advance for helping me solve this.
kentrent
@lowrider57 tube V3 in LS15 still sparking when turned on but with the EQ added the sounds boost to an amazing level.  :))
But I’m still replacing the v3 tube just to be cautious since ARC said that’s not normal. 
The EQ is a good temporary fix. Please keep an eye on the preamp for any shorting out or shutting down due to the tube.
:-)

@lowrider57 im waiting for the DAC to arrived.  We’ll see if its fix the problem for good.  Thanks 
Hey,

So, some thoughts.

If you have some standard electrical wire - i.e. the kind that runs inside the wall - you can use a piece of the ground wire, cut it down and make a jumper wire for the XLR if using SE input. If you have any music on your phone, use a 3.5mm to RCA adaptor and run it directly into the amp. At least you can isolate where the problem actually lies.