Martin Logan CLSIIz - adding more bass?

What about the REL Stadium? Most CLS owners I've corresponded with claim this is the sub to have.

Thanks for everyone's responses...what about the crossover. Should I used an electronic one or a passive one?

ELECTRONIC IS THE WAY TO GO. However.....you really need to find one that is transparent enough to let the system benefits from bi-amping to show thru. Otherwise you end up hardening the overall sound. After a LONG search for an outboard electronic x-over for use with my Apogees, I can recommend the HSU outboard electronic x-over and at $459, it is a steal. I recommend the stock x-over point of 90 HZ, but you can set it lower with plig in chips. It has a 24 DB per octave slope for the high pass section (your CLSs) and 24 DB per octave for the low pass section or an all pass output which allows you to pass a copy of the input signal to the sub or elsewhere. You will immediately notice : more dynamics, greater output, greater transparency & ease and a larger, better defined soundstage. Not bad for a $500 tweak.

I have the same speakers and recently purchased used the kinegistic sw800, the same subs reviewed by aboslute sound with the m-ls and deemed the "super system", or something to that effect, still experimenting but they are seemless without the booming effect; my experimenting is somewhat more complex because i am using a meridian 568 processor through which i'm setting the controls; i believe there is a demo pair for sale on audiogon; steven

Hi Alex1, I tend to agree with Jab on finance and powercord. Check it out carefully with others who are familiar with the rest of your gear. Hybridizing electrostatics with a sub is always tricky and expensive. MLogan CLS11z specs read 35~22kHz which is in fact a FULL range music speaker (unless you intend a HT purpose). My own MLogan Aerius' bass is ample in a small room although it's low limit is 40Hz. What interconnects are yours? I've read that MLogan eng. development were in collaboration with Monster cables. That history is important to the end user. Monster do have some very good hi-end cables recently, maybe worth to check it out. My Aerius and amps are using mid & hi-end Monsters. I know the bass is there because the sound is 3D! Another thing to check is the amp, some tube amps have a hump in the upper bass, so giving a FALSE perception of a "suck-out" of lower bass in a "neutral" speaker. Consult other VTL owners about that. I sold my ARC VT60SE because of that phenomenon, but I'm not sure about your amp,Something you have to check. If the suggested cables work, you would have enough money left (from your budget)to buy another stack of audiophile music. Regards, Phil.