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Any comments on DAC going direct to power amplifier or to pre-ampliifer?

My local retailer HIGHLY RECOMMENDS the use of a pre-amplifier.  Bricasti believes that going direct to a power amplifier sounds better.  And, I also know that everyone had a "different opinion" about going direct or using a pre-amplifier.  

I am running my Bricast1 M1 SE DAC direct to my Hypex NCore NC400 Bridged Mono Block class D power amplifiers (no pre-amplifier) and like the sound quality very much.   

For me, the sound is more natural and clearer by going direct to a power amplifier. Of course, I think the M1 SE DAC has special “custom" circuits in the analog section to make it sound so good. I returned home and listened to my system.  It sounds terrific and I continue to enjoy and recommend the Bricasti M1 SE DAC.

Please note that we removed the R141 (circuit) from my Hypex NCore NC400 bridged mono blocks, thus lowering amplifier gain by 14 dB, requiring 14 dB higher M1 volume setting for same playback level.  Bricasti says the goal is to have the M1 CLOSE to 0db front panel attenuation.  If you reduce the volume on the M1 SE DAC, you cause more bit reduction meaning you lose sound quality.   We discussed this modification with Hypex and they approved the removal of the R141 circuit.  They suggested we be very careful removing the 4 R141 chips (for my 4 NC400 amplifiers) to avoid board damage.  

I noticed that many of the newer DAC’s (even the new Ayre QX-5 Twenty DAC and many others) have volume controls meaning their DAC/Pre-amplifiers are designed to go direct to a power amplifier (as an option, of course).  

What are your experiences of going direct to a power amplifier or using a pre-amplifier?  Have you compared going direct vs. going to a pre-amplfier and noticed any sound quality differences?  Have you gotten different results from using different DAC's and amplifiers?   Your comments are appreciated.  Thanks.





hgeifman
georgehifi's avatar
georgehifi
10,312 posts
 
I find that even the best digital components with well executed designs (dCS, Berkeley Audio Design, Bricasti, Weiss, etc) are still no substitute for a well designed, quality analog preamp.
Yes, they can be, and better, but you must use them in the top 25% of their full output, if below they can strip bits of the music and reduce resolution.
Bricasti, know this and on their vc they give you internal total gain adjustment to lower the gain so you can use their vc the the top 25% of full.

Wadia, Mark Levinson, and others also knew this years ago and here is Wadia’s instructions for this on three of their units, other had it too. Page 6 of the first two pdf’s.

http://www.wadia.com/ContentsFiles/20ef6f0f-c959-4e83-87a8-42526b37becf.pdf

http://www.wadia.com/contentsfiles/25401fda-06b6-4c3a-e028-47fdfed426ba.pdf

Page11
https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwio2MLrmZbUAhWHLpQKHa5DBGIQFgg2MAQ&url=http%3A%2F%2Fpdfstream.manualsonline.com%2F2%2F2318835c-2846-49ef-a25a-21ac9649bd17.pdf&usg=AFQjCNHBroBScCMkOBNe5ThVpdLFA8idJA

Cheers George
jon2020's avatar
jon2020
986 posts
 
Yes, they can be, and better, but you must use them in the top 25% of their full output, if below they can strip bits of the music and reduce resolition.....


So, we can easily compare direct to power amp at top 25% of full output of dac’s VC vs with preamp and then decide with our own ears.

This is a very simple A/B and we can all share our experience with any of the dac’s listed above.

J. :)

georgehifi's avatar
georgehifi
10,312 posts
 
Yes it’s a common big mistake when owners use their CDP/DAC internal vc well below 50% of full and say it’s rubbish compared to a preamp, what their hearing is only maybe 10 or 12bit resolution instead of 16-24bit.

If you have too much gain and it’s way too loud so you can’t use it at no less than 25% of full, then the best option is to leave it up full and use a passive preamp after it to the poweramp.

Cheers George
hgeifman OP
2,155 posts
 
Okay.  I changed my mind about having my DAC going direct to my power amp. The volume control in most DAC's (including my DAC) is indeed implemented in the digital domain and, therefore, when adjusted down, bits are lost AND so is the sound quality. This is a fact of digital volume controls. In other words, reducing a DAC's volume causes bits to be dropped resulting in reduced sound quality.

As an experiment, I discovered that my 2nd DAC sounded better than my first DAC both going direct to my power amplifier. My assumption is DAC #1 was dropping more digital bits then DAC #2 causing the sound quality differences. Based on this experiment, I am now considering using a pre-amp.

I also continue to believe that everyone has a different opinion on going either direct to a power amplifier or using a pre-amplifier. I believe these differences are because we all hear differently and different equipment sounds different in different conditions. Some DAC's may drop bits in different increments (I do not know). 

I plan on adding a preamp/DAC to my audio system shortly.  
georgehifi's avatar
georgehifi
10,312 posts
 
As Wadia and Mark Levinson say with their dacs/cdp players with digital domain volume controls.
Is that they must be used in the top 25% of their range to get the best sound from them, that is why they put adjustable output links inside in the analogue stage to give different gains, so then the digital volume control can be use in it’s top 25% range. Bricasti do this also with their M1, it’s done different but the end result is the same.

If you can’t do this with your dac or cdp, then the next best is to do it with a passive volume control after the dac, set it, so that then you can use (the digital volume control) in the top 25% of it’s range.

No need to buy an expensive preamp, because you’ve already proved your dac has more than enough gain, too much in fact because you can’t use the digital VC in the top of it’s range.

Cheers George

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