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Do you have any comments of running a DAC directly to power amplifier with no preamp? I can think of several advantages to not using a preamp but would really like your opinion, since, it seems, many of us are opting to go direct these days.
For example, let us assume the DAC goes straight into the power amp's XLR inputs; the DAC's volume control is digital, runs in 32 bits (or 24bits) and is very well implemented.
I have been told that some users do not like the idea of running a volume control well down in its range so use fixed attenuators but many have reported a loss of SQ in the process. Others have stated that they prefer the sound through a preamp stage. And, as expected, others state the sound quality is improved when the preamp is eliminated.
I hope to test these options, with and without the preamp, shortly and am interested in hearing about your experiences.
Any comments on this would be appreciated.
Follow Ups:
"in practice, there is".
Yogi Berra's caution applies here.
I've used passive attenuators to great success with a source with a very low output impedance (75 ohms), but it is all a matter of matching. For many years, I resisted the assertion by others that for one reason or another, an active preamp provides better dynamics. That didn't make sense for me.
When I changed from using that particular CDP to a new DAC (which sounds better), the attenuator solution didn't works as well. When I purchased a new preamp, I found that low level dynamics were far better using the preamp.
The notion of adding an active stage improving the sound still doesn't "make sense" to me but it seems to be the case in some situations. Now I finally understand what Ralph Karsten and Charles Hanson have been saying all along.
Experiment.
there is only one way to find out is very appropriate here. My DAC is 50
ohms out Z and the GD in the other thread is just 10 ohms! It's calling me!
E
T
High output low impedance sources will drive sensitive high input impedance amps fine. When I took out my preamp I got rid of a gain stage I did not need that was acting as an attenuator over 95% of the time.
Just try it and see.
E
T
I'm no expert, but from my DIY tube amp experience I can say that impedance mismatches from source to amp can alter the frequency response. This may not be an issue with certain combinations of gear, or mismatch may produce tonal changes pleasing to the listener, or it may interfere with the desired result. I'm not advocating measuring anything, I'd just listen to different combinations of source, preamp and amp and see what works for you. For me, I like a tube preamp with my various tube and solid state amps. Wish you luck!
I have quite a bit of experience with a direct connection setup. In my case this has been dCS DACs into tri-amplified ATC monitors (no speaker cables either with this as the power amps are built into the speaker cabinets).Broadly speaking the settings of DAC volume control have been similar to those noted by Tony Lauck. Interesting as the input sensitivity of the power amps is quite high at 0.5V. I have tried in-line attenuators to try to preserve higher volume control settings (and thus resolution with a digital volume control) but found this to hamper dynamics (impulse?) although not dynamic range. dCS say that resolution is lost with the control set below -20dBfs although I can go well below this without actually hearing any such loss.
Results are mixed. Broadly as the dCS DACs have evolved over the years direct connection has subjectively improved. I would say it was unsatisfactory with the early "classic" range, excellent on small scale music with my Paganini set and excellent on these and on larger works with the Paganini once the current S/Pdif protocol was installed which allows transmission of rates up to DoP (I cannot understand why this subjective improvement should be so with redbook but there it is).
Although it is quite feasible to gain much enjoyment from the sense of clarity that the direct connection brings nevertheless eventually I have always felt happier when returning to the addition of a pre-amp, either tube or SS. Unfortunately, and no matter how much I have liked the direct setup, I end up feeling that the direct connection is just too sterile or matter of fact, particualrly with large orchestral works. Maybe its just familiarity I want? Anyway remember that direct connection from storage/conversion to amps was not experienced during the original recording's production as a pre amp (in the form of a mixing desk) was always in use. So maybe direct connection is actually of less overall fidelity than theory might suggest.
Edits: 08/18/15 08/18/15 08/18/15
I run a Mytek Stereo192-DSD directly to my powered Focal monitors, using balanced XLR connections with the monitor sensitivity set at +4 dBu. The Mytek has the extra IV resistors jumpered to lower the output by -6 dB. It is set to have volume trim of -14 dB and I use the digital volume control option in the Mytek rather than the analog, because it avoids a bunch of op-amps and sounds cleaner. With typical audiophile recordings the volume control is set at about -15 dB of digital attenuation for normal listening, turned up to -6 dB for large scale music such as Mahler symphonies. Although this system is capable of undistorted peaks to 115 dB at my near field listening position I don't hear any noise as a result of running the DAC directly into the amplifiers of the speakers. Note that the digital volume control in the Mytek works at the 32 bit level, so it is not losing any resolution, just that the residual converter noise fed to the speakers is at a higher level than it would be with a passive volume control or low noise preamp.
When playing "loudness wars" recordings, the volume control has to be turned down to about -25 dB to -30 dB, but these recordings are, by their nature, junk and hence there can be no concern about "sound quality" when playing them. (Sound quality is further improved by hitting the power switch.)
My speakers have another setting, -10 dBv. With this selected, and especially without the -6 dB output reduction from the Mytek jumpers I would have had to use substantially more digital volume control and would probably have found the results unsatisfactory. I do not use digital volume control in the computer, but I could because the computer sends 32 bits to the DAC. However, this would be a bad idea, because the computer might blast out "You have mail!" at full volume in case of a software glitch. With the volume controled by the DAC the risk of blowing things up doesn't exist. (Actually, my system will play cleanly with the volume turned all the way up, but at my usual listening position it will take only a few seconds before my ears start ringing, hence I don't do this.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I have run this hot-rodded combo before and have always preferred the linestage option.
I do like the Z-Systems units for switching and the reclocker/upsampler portion,not to mention that you have a digital parametric to cure any ills.
For $700 its a no-brainer.
Generally speaking,I have found a loss in SQ and especially bass/midbass drive and top-end.
Another thing to consider is the linearity of the dac,when presented with lower level digital input (digital attenuation).
It will be interesting to see how this thread develops.
Tom:cat
I use a NAD M51 as the DAC/Preamp to an A23 driving a pair of Thiel CS2.4's with great success.
I wasn't happy with the Berkeley Audio DAC-2 driving same, or driving the Ayre V-5xe
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