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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
 
A key for impedance mismatch is a tipped up balance (no real bass)
It’s more to do with the source, if it has an output coupling capacitor being too small (in uF), which yes raise the ouput impedance, when in conjunction with the input impedance of the passive. This forms high pass filter (a low frequency roll off) that can start too early and chop out some of the low bass.
But it’s a simple fix, replace the coupling cap in the source with 2 or 3 x the uF (microfard) and while at it a better quality one.
That's why I prefer sources with direct coupled outputs, no cap to worry about. BEST CAP IS NO CAP.

Cheers George
dragon_vibe
430 posts
 
No matter what the manufacture claims about their volume pot in the DAC I have nearly on all accounts found them to be utterly crap. From personal experience any DAC will sound better with a transparent Pre-Amp sitting between them.

Finding a Transparent musical pre-amp is not as easy as you may think. From all of the pre-amps iv owned i found the MP-1 Atma-Sphere Pre-amp to be the best for me. Dynamics improves by a large margin.

shadorne's avatar
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shadorne
7,477 posts
 
Benchmark make a DAC with built in pre-amp.
mitch2
3,967 posts
 
First, you need to make sure the VC does not result in throwing away bits.
Current best options include those by Empirical Audio and Metrum Acoustics that adjust the reference voltage and operate out of the signal chain.  To me these still retain similar drawbacks as using a really good passive pre, unless a buffer is added.
As dragon_vibe points out, a good, transparent preamp improves on a passive, DAC based, control (for most) by optimizing the signal going into the amplifier(s). In many/most cases, dynamics, tone and dimensionality are improved IME.
A good unity-gain buffer will do the same thing.  I recently auditioned Tortuga's tube buffer and when paired with a passive I have here, I found it to be quiet and very good sounding, particularly for the price.  Anybody running a passive pre should give it a try.  Empirical Audio offers their Final Drive transformer buffers, which would also be worth a try with any type of passive.
One transparent solution I can recommend highly is the SMc Audio VRE-1, a buffered preamp with your choice of 6dB-gain (through the Lundahl transformers) or optional unity-gain.  I use a unity-gain buffer version with a Shallco attenuator built using AN Tantalum resistors.
guidocorona
4,298 posts
 

Hello Dragon_vibe, I do not claim of havving heard every DAC on the market today, far from it. Hence, I am not in a position to claim that all volume control built in DACs are wonderful. On the other hand, I have solid reasons from personal experience to assert that a broad claim of all DAC VCs being worthless is equally invalid.


I have been enjoying a Rowland Aeris DAC for several years. This device has a volume attenuation/gain based on controlling the reference voltage, as you can read in one of the technical articles at:


http://jeffrowlandgroup.com/kb/categories.php?categoryid=205    


I have used Aeris with three excellent preamplifiers: ARC LS2-B, ARC Ref3, and the incredibly transparent and resolving battery-powered twin-chassis Rowland Criterion. In the end, I determined that in my particular system, I could very well drive my Rowland M925 monoblocks into the Vienna Die Muzik speakers directly from Aeris, without an interveening line stage. Why? Because the sound I achieved even without linestage was wonderful, from both an analytical and emotional point of view.


But why am I using "was" instead of "is"? That is because in the last three weeks I have replace the external Aeris power supply with the new Rowland Power Storage Unit, which feeds Aeris pure DC through a bank of ultracapacitors that isolate Aeris completely from the AC grid. And the result to my ears is... Simply mesmerizing.


Will I ever insert a line stage again into my system? I have no idea.... I am not in the habit of mortgaging the future. Nor am I in the habit of claiming that what I have is "the best in the world", or other such juvenile boasts. The only thing I know for certain is that my music making system has risen to a performance level I have never experienced until now, linestages or not.


Regards, G.




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