2. amps-preamps
  3. 1105628637

Would a preamp help?

I've just changed around my system completely... I went from a multichannel setup based on the Theta Casablanca to:

Theta David CD/DVD transport
dCS Purcell upsampler
dCS Delius DAC
2 x ARC VT 100 Mk IIIs
ProAc 3.8s

Cabling is Kimber Orchid AES/EBU from CD/DVD to Purcell, dual Kimber Orchid AES/EBU from Purcell to Delius, Kimber Silver Streak XLR->Kimber Silver Streak Y Splitter from Delius to amps, and dual runs of Kimber Monocle XL from the amps to the speakers. Everything is powered by DIY VH Flavor 1/2/3 PCs to a PS Audio Power Director.

I'm finding the resolution improved, but the music seems to lack some immediacy and drive--the slam factor. Bass is also a bit overblown, but I think that is attributable to room placement issues and bass I wasn't getting before.

I'm trying to figure out whether the issue is a whole slew of new cables and break-in issues--the Orchids and SS are all out of the box--or whether its the lack of a preamp. If you think a pre would help, any suggestions? I guess my immediate reaction might be to find an ARC LS25 Mk II or Ref 2 Mk II, but its a pretty expensive upgrade...
edesilva
gregm
3,405 posts
 
I would look for a solution before purchasing a pre...

What you describe sounds like the Delius isn't driving the amp too well -- i.e. the dac's output impedance is too high at certain frequencies. This is surprising though... what's the VT100s' input Z? I assume the Delius is 600ohm or less.
Items like the SCE mentioned above by Listener provide a "buffer" service so as to achieve a better transfer (i.e. a lower source impedance to achive better voltage transfer to the load/amps).

A pre would add another stage to yr chain. It would drive yr amps more easily at the expense of some resolution (unless you go for the exotic, i.e. Blowtorch, & the like).
edesilva OP
768 posts
 
Thanks for the responses... I'll google SCE.

The dCS website sez the Delius output Z is 1 ohm... According to the ARC website, the VT100 has an input Z of 200 k ohms for the balanced inputs, 100 k for SE; I'm using balanced.

Hmm... Does the fact that I'm using a Y splitter off the dCS output alter the normal compatibility concerns?

I'm also going to have to check my Delius; reading the website just now, it appears the output is selectable 2V or 6V via software, and I'm not sure where its set--I'm assuming 2V is the right #. If it was set at 6V, would that explain anything? Given the #s, it doesn't seem like the Delius output Z could be construed as too high...
maximmd864
15 posts
 
You may also try some kind of a buffer instead of preamp if you don't need a volume control on it directly. I think bvaudio has something like that called sound refiner, check their website.
edesilva OP
768 posts
 
Thanks for the input. I guess I may pull the LS16 out of another system and see what happens...
gregm
3,405 posts
 
Edesilva: if you're riving two 200kOhm loads in parallel, the Delius is looking at an equivalent 100k load -- a very easy /trivial load for a 1ohm output Z device...
If you can set the delius to 6V output do so -- you might be feeding insufficient voltage into yr amps.

Generally speaking, with 1ohm output (more or less across the AF band, right? -- or is it 1ohm only at 1kHz?) you certainly don't need another pre (yr Delius already includes one pre)!
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