Promitheus and Wyred4Sound

Excuse me for saying so, but in my view buying the SX-1000 mono blocks to power modest 2-way speakers like your Quads is like putting a 600 HP motor in a stock VW Bug. It's major overkill and if pushed near its max it will rip that vehicle apart. Even the SX-500 amp would give you twice the power you would ever use with those speakers (and much more power than the speakers are rated to handle).

I have had both the W4S ST-500 and STI-500 amps in my system. They are probably the most dynamic sounding amps I've ever experienced.

My advice would be to buy the STI-500 integrated amp. You could try your TVC straight into the power amp section via the HT input and compare it to going through the STI-500's built-in passive preamp. Don't be surprised to find you're not gaining anything by using the TVC.

At present I run my CD source through a tube line buffer, then into the STI-500's preamp inputs, which works quite well. Curiously I like my phono stage run directly into the STI-500's preamp inputs. It's a battery-powered phono stage and doesn't seem to benefit from the extra stage of tube "sweetness."

My point is that choosing one of the Wyred integrateds might open up some options for you. I didn't notice any decrease in performance by moving from the basic power amp to the integrated amp as the internal preamp section is very transparent. Plus you'd gain remote control.

Plato,
I think of it as "hot rodding" rather than your analogy :-). But your point is well taken. The reason for SX-1000 is for future upgrades and I think a high powered amp will drive the Quads well. I believe when you say that the W4S amps are the most dynamic amps you experienced. Another member who is a big fan of Plinius mentioned that the SX-1000 were better than the Plinius SB-301 he had. He has not compared his SA-References to the W4S simply because it was too much efforts to move the amps and besides he was worried that he might find that the W4S may be better than the References.

Anyways, I do not want the integrated, as I know the TVC very well by now. I should have named the thread as "Passive Preamps and W4S". My CDP has a output of 2.2V and it will never drive the SX-1000 to MAX as it requires 2.95V. "No remote" is fine with me. It is a small sacrifice over the sound that I currently get with the TVC.

I did check with W4S and they don't know of anyone using the SX-1000 with TVC. I can request them to change the "gain" on the SX-1000 before ordering. But I would first like to hear from people who have had a W4S+TVC in their systems.

Thanks

I'd be a little concerned with the 2.95V input sensitivity of the SX-1000 when using it with a TVC or any passive for that matter.

Yes Clio09, that is what I am thinking. W4S did mention that they can double the gain to 54db. The question is, will this sensitivity change make any negative impact on sound quality?
W4S also mentioned that with the current configuration of the SX-100 and TVC supplying 1.5V, it will produce 285W at 8 Ohms. If that is the case then fine. But I don't want the amp supplying 1.5V at the 20th or 21st position of the volume knob, out of the available 24 positions. I would rather have the 285W reach at 16-17th positio on volume knob. That way the TVC and the attenuation will give me the best sound quality. I may be wrong and open to suggestions.

Wow 54db is a lot of gain. I am not familiar with the W4S designs, but I'd be curious what that the input sensitivity would be in that situation. I think your concern with regards to volume control position are valid from a flexibility perspective and not necessarily sound quality. I prefer my settings around 12 or 1 o'clock for average listening volume.

The input sensitivity would be 1.5V as per W4S. Infact when I asked if the sensitivity can be made to 1.5V, they mentioned that the gain would then be 54dB.
You are right, I am more concerned about flexibility and I need more headroom (in case). With the NADs I set the knobs at 12'O clock position and I am already reaching the room limit. The NADs have 770mv sensitivity. The TVC creates a magic either at this setting or at +- 1 position from 12'O clock.

The new Musical Fidelity M6PRX also seems to have some great specs. But I have seen many folks 'goners not much happy with Musical Fidelity product. The M6PRX is a bit out of budget though:

http://www.musicalfidelity.com/products/M6-Series/M6PRX/M6PRX.asp

I have the M6PRX. It's a beast. Power forever and wonderful, warm, class AB sound. I also have a W4S 125wpc (well, really 100 below 1%thd) amp in another system. I've done the compare.

The W4S is a wonderful, detailed, open amp. It sounds great and if I only had a grand to spend on an amp that's what I'd buy in a New York minute.

But where the W4S would be described with terms like 'detailed, lean, analytical', the MF is 'warm, alive, organic'. Sort of what you'd expected comparing an ice-power to a very expensive and refined AB amp.

They both sound great. But I'm keeping a classic 'AB' amp for my main system for the foreseeable future.

PS: I'm a big W4S fan, I have two of their dacs. Great stuff and a wonderful company.

Mike,
Thanks for your input. I purchased the Parasound A21 in Feb this year. Pretty happy with it.