Jeff Rowlands Amp and Dac vs. VAC amp and DAC

Thank you, Ricred.  Good info.  Is the adjustment you are referring to internal to the unit, or is it the volume control that is on the front panel?

Rinpoche, gain is the relation between the output voltage of a circuit or component, and the input voltage that is provided to that circuit or component.  In the case of a component having a volume control, such as a preamp, it is usually specified based on the control being at its maximum possible setting. 

Although for a source component such as a DAC it is probably more proper to refer to maximum output level, or maximum output voltage, rather than gain, since the component is not being provided with an input voltage in the usual (analog) sense.

Best of luck as you proceed.  Regards,
-- Al
 

On paper the Rowland is a better match for those speakers. I suspect.  

Both Rowland and vac gear is top notch sound wise with trade offs other than sound quality  as you see which is often the case with ss versus tube gear.  


Matched optimally and set up well I would expect more similarities than differences between the two in general though I have not heard the specific models in question.  

If you can hear both and compare that would ideal.   

Al,
The gain can be adjusted on the front panel or via the remote. Rowland recommends that you adjust it so the two blue LED lights on the front panel are of equal brightness when used with a preamp. I have it about 4 clicks up from the recommended setting. I have found that to be optimum in my system...great gain, clarity, and it allows me to open up the volume control. Come to think of it, I just changed speakers that are more sensitive. I'm going to adjust the gain to the recommended setting to see which way I prefer.

Thanks, Rick. 

Part of the concern I expressed about that issue was the possibility that if the DAC's volume control would have to be set in the lower part of its range, and if the volume control function is implemented digitally (I don't know whether or not that is the case in the Aeris), its sonics might be adversely affected as a result of what is referred to as "bit stripping."  Which can occur to a greater or lesser degree, or not at all, depending on the design of the particular DAC as well as on the particular volume setting.  And I raised that point in connection with the particularly high gain that most VAC amps provide, which (everything else being equal) would necessitate a lower setting of the DAC's volume control.

I see that your Rowland Corus preamp provides overall gain that is "Independently Programmable 0 to 20 dB on each input."  It would be relevant to the discussion to know what you have that set to in your system, or if it is set to some default value, what that default value is.   If that gain is set to a high value it would necessitate a correspondingly lower setting of the DACs volume control, to enable the preamp's volume control to be used in a desirable part of its range.  Thereby increasing the possibility of adverse sonic effects due to bit stripping, if the DACs volume function is implemented digitally.

Pending knowing how that is set in your system, though, my guess is that the high gain of the VAC amps would not be a problem for Rinpoche. I say that based on your results together with the fact that the 5 db or so higher gain of the VAC amps, relative to the gain of your Rowland amp, closely corresponds to the approximately 6 db lower efficiency of her speakers compared to yours.  Which would result in essentially the same overall system gain, aside from preamp differences.

In any event, though, I would suggest to her that if she obtains a high gain amp such as one of the VACs, and also eventually purchases a preamp, that high gain preamps be avoided.  Examples of high gain preamps include many Conrad Johnson models, which provide gains in the area of 25 db or so.  A preamp providing a gain in single digits, or at most around 12 db or so, would be a much more suitable choice.

Best regards,
-- Al
 
 

Thank you all. This has been very helpful and informative. I have learned a lot. My experience of listening to the JR 625 (upgrade) and the Aeris as well as the VAC was great. If I didn't have the VAC to listen to after I would be very happy with the JR equipment. And it is easier overall to work with (for film and TV). But, I think that the VAC had a little extra magic. I guess that is the tube vs. SS issue. Once I get all the costs and details of what it might cost each time I have to change the 4 main tubes, I will decide. I know I will be happy with either one, but if I go with the JR will I always be thinking "what would the VAC have been like?" And the first time I have to bias myself I will be thinking "should I have gone with the JR!" If these were the biggest problem one had in life, it would be amazing. Thank you all and if there are any other voices of wisdom I would love to hear.