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
Well I did a little on line reading regarding your speakers which causes me to suspect the combination of your ARC stuff and the KEF may be your problem. Your speakers seem to be considered ’neutral speakers’ (at best). You seemed to like them when driven by a (very) warm vintage receiver). You are hearing the results of you amplification choices quite clearly. You seem to like a warmer toned system’s sound but with better resolution than you get with the old Mac.. Very common in audio.

Now you change to electronic’s which, tonally speaking, might be voiced to be neutral (at best, IMHO, very cool). So you are doubling down, so to speak, and get the sound inherent in both. For you this sound is not synergistic in that it doesn’t produce the tone you want, not that either the electronics or the speakers are wrong, they just don’t sound as you would like when combined. I would suggest that most of us have been there and done that. I certainly have. That is why most folks will recommend ’matching’ your speaker and electronics. Arbitrary buying will not get you there.

BTW, regarding 4 ohm taps. I’m a bit put off by KEF’s ’recommendations re using only the 8 ohm taps. I could understand why they think your speakers might sound best a 8 ohms (perhaps they think the 4 ohm tap might unbalance their preferred sound) but I know of no reason you should not try them. Your speakers may have have a nominal 8ohm rating but this is far from indicating that they have a minimal 8ohm ’curve. Reviews point out that they have a minimal ohm droop to 3.8 ohms. Were I you, I would research this issue before I just walked away from it based on someone from KEF’s opinion. I like warm toned systems and have most always operated off 4ohm taps.
On the rear of the VT100 mki there is a place for inserting jumpers to change the inputs from balanced to SE.  Was the seller using balanced or SE Interconnects?  
You can download the VT100 manuals on the Audio Research site.  The manual shows where the jumpers are.
The balanced input impedance is 200K.  SE is 100K.  Big difference.  
IMHO.  Check that first.

Do you have a multi-meter with spring-loaded hook clips?  If so, check the amp bias to make you have power.

As to the LS15, disconnect it from the amp (power off).  Power it back up and see if the sparking goes away.

Let me know and we can go from there.

Have had a lot of ARC gear over the years.