• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Combo DAC/Amps: How big a compromise?

MediumRare

Senior Member
Patreon Donor
Joined
Sep 17, 2019
Messages
475
Likes
355
#1
The detailed analyses of the latest round of combo DAC/Headphone Amps has focused on their dazzling SOTA DAC sections. But the measurements of the amp sections has been something of an afterthought, with only a handful of measures checked. A prime example is:
https://www.audiosciencereview.com/...-dx7-pro-dac-and-headphone-amp-reviewed.9446/

On the other hand, the latest breakthrough headphone amps, like the THX AA 789, Monolith 887, and SP200 have very detailed analyses. Here's another example: https://www.audiosciencereview.com/forum/index.php?threads/jds-labs-el-amp-ii-headphone-review.9973/

So, the question remains unanswered: How big a comprise in the headphone amp section is there from the DAC/Amp combos compared to adding on a stand-alone headphone amp? Maybe we need some more detailed measurements?
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
22,650
Likes
35,032
Location
Seattle Area
#2
I use such a combo unit every day even though I have the other options at my disposal. At the extreme, the power level is lower in these combo units compared to stand-alone units. And distortion is not state of the art but excellent nevertheless.

I think the "compromise" comes from lack of access to state-of-the-art headphone amplification in the combo units. This will likely be solved over time.

I will review the JDS Element II later today as an example of the above.
 

MediumRare

Senior Member
Patreon Donor
Joined
Sep 17, 2019
Messages
475
Likes
355
#3
I use such a combo unit every day even though I have the other options at my disposal. At the extreme, the power level is lower in these combo units compared to stand-alone units. And distortion is not state of the art but excellent nevertheless.

I think the "compromise" comes from lack of access to state-of-the-art headphone amplification in the combo units. This will likely be solved over time.

I will review the JDS Element II later today as an example of the above.
Thanks, @amirm. What I'm really looking for is the similar charts you did on the EL Amp but on the DX7 Pro.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
22,650
Likes
35,032
Location
Seattle Area
#6
appart for the FR graph the DX7 PRO doesn't have.
And on this, in combo units I can only drive the DAC digitally which truncates bandwidth based on its sample rate. For stand-alone amps, the input is analog and hence no filtering that gets in the way of assessing its bandwidth.
 

MediumRare

Senior Member
Patreon Donor
Joined
Sep 17, 2019
Messages
475
Likes
355
#7
And on this, in combo units I can only drive the DAC digitally which truncates bandwidth based on its sample rate. For stand-alone amps, the input is analog and hence no filtering that gets in the way of assessing its bandwidth.
I understand the technical limitation, but as that is how the unit will be used (DAC -> Headphone section -> HP XLR Out) that's OK.

Both reviews share identical charts for the headamp part...
appart for the FR graph the DX7 PRO doesn't have.
I may be misunderstanding but I don't think so. All the initial (DAC) charts are for "XLR Out", which I interpret to be "XLR Line Out", bypassing the headphone section. Am I mistaken?

Otherwise, it would be very useful to have, for XLR Headphone out, at least:
1574198461933.png , 1574198511736.png , SNR XLR Out at full power, 1574198622764.png

Then we could compare apples to apples (agreeing that we're relying on the DAC to feed - but with these DACs, that's not much of a compromise, right?)
 

JIW

Member
Joined
Nov 11, 2019
Messages
55
Likes
76
Location
Denmark
#8
I think the "compromise" comes from lack of access to state-of-the-art headphone amplification in the combo units. This will likely be solved over time.
At least for the RME ADI-2 DAC/Pro, there does not seem to be this compromise. The "regular" amp even in conjunction with the DAC pretty much matches the above mentioned amps and the IEM output again even in conjunction with the DAC holds the crown for lowest noise at lower levels and both have very low output impedance. In fact, the amps seem to be held back by the DAC (at least on the old version).

With the new version of the DAC with improved DA, according to RME's specs the measurements of the amp outputs should be quite a bit better: THD+N @ +18 dBu, 32 Ohm Load (1.2 W): -114 dB, 0.0002 % compared to -107 dB on the old one, THD @ +18 dBu, 32 ohm load, 1.2 watts: -120 dB, 0.0001 % compared to -110 dB on the old one.

With such performance external stand-alone amplification is superfluous apart from some edge cases where the RME's 1.5 W or when using symmetrical connection on the Pro even 3 W are insufficient. Even there, the mentioned stand-alone amps only gain 3-4 dB using symmetrical connection vs. the RME's single ended connection and maybe 1 dB for either using symmetrical connection.
 

Similar threads

Top Bottom