VAC Owners:Outboard Phono Stage?

Thanks you guys! I wasn't planning to try anything without asking Kevin, but your advice has helped me be more prepared for the conversation.

I found this CD from Granite Audio and here's what they say:

Using this CD to burn-in your phono section will save needless wear on your record stylus and turntable.  Standard music CD's cannot be used for this purpose because their signal level at 240mv to as much as 4 volts would overload your phono inputs, which are designed to handle only about 4mv of input signal.  Also, conventional CD's would have their low frequencies boosted by 20dB more than a phonograph record that was encoded with the RIAA bass rolloff.  So, playing a standard music CD through your phono input could also damage your speakers with excessive bass tones.  DO NOT attempt to play any standard music CD's through your phono inputs.  You can only do this with the Granite Audio Model #CD-101 Phono Burn-In CD.  Our CD is the only one that has been engineered for this purpose.

Alón, yes, that is exactly what I am recommending that you do NOT use. Everything they say in the paragraph you quoted is essentially correct, but no matter how well the CD may be engineered for the particular purpose it cannot control what the PLAYER may do in the event of malfunction, momentary AC power dropouts, etc.

I believe that the moving coil section of the preamp employs a transformer at its input, which would be designed to handle signal levels measured in microvolts (millionths of a volt), and miniscule amounts of current. Misbehavior of the player, caused by the kinds of (admittedly unlikely) events I mentioned could easily put voltages across that transformer that are a couple of thousand times or more greater than those amounts. As well as overloading and stressing circuitry in the preamp that is downstream of the transformer.

Using the KAB device Bill suggested, you would use a conventional CD of your choice, and those risks would be eliminated.

Best regards,
-- Al

Thanks Al and Bill. Your advice and suggestions are appreciated.

If you're open to more questions (anyone jump in here), here are a few that have bubbled up through my dark grey matter in preparation for my new pre:

1. Now that I'll have both amp and preamp able to support Balanced ICs, is there any advantage to having the connection between pre and amp be balanced while all others are single ended?

2. I need to rearrange my rack. Although the Sig's power supply looks really cool with the lit up logo, shouldn't it be as far from my amp and preamp as possible, as in not in the rack? I see the pre stacked on top of the PS in photos, but I thought that was for advertising convenience...

3. Do any of you fellow nut cases cap your unused RCAs on the back of your preamps? Does it make a difference?

I can't wait to get this thing into my system! Thanks all!

Alón

Props to Albert Porter for turning me on to the KAB device. I knew they existed, but he zero'd in on that one, the company is reliable, and you can get the device quickly.
As to Alonski's questions, I can only offer my own experience:
1. Yes, there are benefits to using the balanced connectors even if everything in the chain is not fully balanced. I also like the firm connection made by XLRs. Whether you can hear a difference, I don't know. I have identical lengths of the same cable terminated both ways, but have not bothered to compare on the stretch between my phono stage and line stage.
2. My assumption on separate power supplies was that they were made separate for a reason. I don't know that you have to go to the length of hiding it, but I think power supplies have the potential to throw off a lot of garbage, and getting them isolated from low level audio signals is beneficial. Having said that, I had the tube power supply to my old line stage separated by one rack shelf and it was fine. The 'stacking' thing you see in photos is likely the same thing as having a blonde as a hood ornament on the car- you wouldn't drive it that way. :)
3. When the designer of the Veloce line stage was at my house, we tried the caps on the RCAs and it didn't make a difference on my set-up. Not that it wouldn't on another...

Alón, re your three questions:

1)As you may realize, regardless of whether other interconnections in the signal path are balanced or unbalanced, and regardless of whether the two components in question are internally balanced or not, having a balanced connection between them will reduce susceptibility to ground loop effects (both low frequency hum and high frequency buzz); will reduce susceptibility to noise pickup in the interconnects; and in some cases will reduce cable effects and cable differences. On the other hand, none of those things may be significant issues in a given setup. And the balanced vs. unbalanced alternatives will call into play different interface circuitry in the two components, and which may be better will depend on the particular designs.

So what I would suggest is asking Kevin for his opinion and/or trying it both ways.

2)Hard to say what minimum amount of separation would be ideal without having intimate knowledge of, and hands-on experience with, the particular design. Sounds like another question for Kevin.

3)I use shorting plugs (not caps) on unused RCA inputs in my system (not on outputs, of course, which should not be shorted). I doubt that they make any difference, but I suppose it is remotely conceivable that they could reduce noise pickup on unused inputs, that might to a small degree couple into the signal path. IMO caps are unlikely to accomplish anything more than keeping out some dust particles. Other opinions may differ, of course.

Best regards,
-- Al