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
@Kentrent, the jumpers must be present on the rear of the amp (in the two places where it says "use jumper for single-ended") if and only if the connections between preamp and amp are made with RCA cables. The jumpers must be removed if the connections between preamp and amp are made with XLR cables.

@jea48
Jim, it looks like I provided an answer to some of the questions you directed to me in one of your recent posts while you were composing that post. So as I said it seems very possible that if the jumpers are installed while the amp’s balanced inputs are being used it "could make the preamp very unhappy." And the caution you found in the manual about not using the mute function while the volume level is high would seem to add credence to that.

Regarding your question about the volume difference, the OP had said earlier that:

At the seller house setup, he only turn on 30% and i can hear music pretty loud. But when my setup i had to crank up to about 70% to hear loud.

... And I note that the seller’s speakers are spec’d as being 6 db more efficient than the OP’s speakers. I’m guesstimating that would account for about 1/3 of that 40% difference. And perhaps differences in the source components and source materials that were used, room effects, and differences in listening distance might be contributing to some extent as well. But in any event it would seem that all bets are off until the issues of the sparking tube and the shut-downs of the preamp are resolved.

Best,
-- Al


@jea48 well, i dont even have the jumpers. Would it damage the system if i dont have jumper connected while using rca?
@almarg, the random shutdown is resolved for now.  But about the jumper, i dont have anh jumpers connected to the xlr. 
Would it damage the system if i dont have jumper connected while using rca?
Damage, no.  Read the owners manual why the jumpers should be installed when using RCA single ended ICs.

Didn't the seller give you the jumpers for the amp? Surely he mentioned them.
Would it damage the system if i dont have jumper connected while using rca?
No.  It just wouldn't be sonically optimal, and it might result in a bit of hiss and/or hum.  

Regards,
-- Al