connecting integrated amplifier (pre-out) to headphone amp
Mar 15, 2018 at 7:43 AM Thread Starter Post #1 of 20

Naha

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At the moment i have an audio system i am quite happy with. it consists of B&W CM9, Rotel-RA1929, Bluesound (i use this for streaming musig), TV, PS4. At the moment all the sources are connected to the Rotel.
Recently i decided to buy a pair of Focal Elear hoping i could pug them straight into the Rotel for some more private listening sessions but it seem that the impedance for the headphones out in Rotel is too high (100 ohm) so the sound might not be stellar for this headphones straight ot of the Rotel.
That being said i started to look arount for an amp design for headphones. So far i have set my eyes on Burson Soloist MK2 but the major oroblem for me is the connectivity of the sources so that i can use the headphones for any of them...
I was thinking that if i will connect the Burson to the pre-out of the Rotel that should work fine for what i need but honestly i have never used a pre-out and i have some doubts:
-Having the pre-out connected will i be able to switch and listen to both the B&W speakers (plugged directly into Rotel) and Headphones (one at a time)?
-will the sound be ok in the headphones if i use the signal from pre-out to feed the Burson?

Thanks in advance!
 
Mar 15, 2018 at 8:43 AM Post #2 of 20

ProtegeManiac

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At the moment i have an audio system i am quite happy with. it consists of B&W CM9, Rotel-RA1929, Bluesound (i use this for streaming musig), TV, PS4. At the moment all the sources are connected to the Rotel.

Are you sure about the Rotel's model number? I Googled it and can't find anything.



Recently i decided to buy a pair of Focal Elear hoping i could pug them straight into the Rotel for some more private listening sessions but it seem that the impedance for the headphones out in Rotel is too high (100 ohm) so the sound might not be stellar for this headphones straight ot of the Rotel.
That being said i started to look arount for an amp design for headphones. So far i have set my eyes on Burson Soloist MK2 but the major oroblem for me is the connectivity of the sources so that i can use the headphones for any of them...
I was thinking that if i will connect the Burson to the pre-out of the Rotel that should work fine for what i need but honestly i have never used a pre-out and i have some doubts:
-will the sound be ok in the headphones if i use the signal from pre-out to feed the Burson?

You can't use the Preamp Output out of an intergrated amp - or anything really - into a headphone amp or into another integrated amp. That's basically going to put two preamps in the same chain controlling the volume, and when the first one is also an active preamp, you have to figure out what level to set it to so you don't send out a signal far above 2volts.

You're supposed to use the Tape Out on an integrated amp that way whatever source is selected will just have its signal sent over to that output unaffected by the integrated amp's potentiometer.


-Having the pre-out connected will i be able to switch and listen to both the B&W speakers (plugged directly into Rotel) and Headphones (one at a time)?

If you use the Tape Out/Rec Loop output and you're going to use headphones, some integrated amps can be left off, as long as source and tape out selectors are analogue buttons.

If you were running the speakers and then want to temporarily switch to headphones, or the integrated amp doesn't work that way when switched off, just set the integrated amp's volume control to the lowest setting. When you want to temporarily return to the speakers, then set the headphone amp's volume control to the lowest setting.
 
Mar 15, 2018 at 10:25 AM Post #3 of 20

Naha

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Thanks a lot for your quick reply.
Are you sure about the Rotel's model number?

Sorry i meant to write Rotel RA-1592. it came out a bit tweested

You can't use the Preamp Output out of an intergrated amp - or anything really - into a headphone amp or into another integrated amp. That's basically going to put two preamps in the same chain controlling the volume, and when the first one is also an active preamp, you have to figure out what level to set it to so you don't send out a signal far above 2volts.


On Rotel’s website they say:
The RA-1592 has a set of preamp outputs labeled PRE OUT. The currently selected source input is available from this output. Typically the PRE OUT output is used to provide a signal to another integrated ampli er or power ampli er, which is used to drive remote speakers.

Doesn’t this contradict your statement ? Or you have bad experience using that output? Sorry i am not trying to pick here. As i said i never used that output before. so i have no clue myself.
To my understanding once you make the connection like that, the volume is controlled by the pre-amp (in this case Rotel) while the thing that comes after that just gives the power.

You're supposed to use the Tape Out on an integrated amp that way whatever source is selected will just have its signal sent over to that output unaffected by the integrated amp's potentiometer.

Unfortunately this amp i have does not have a TAPE OUT. Waiting to see your feedback on the pre-out.
Thanks a lot again.
 
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Mar 15, 2018 at 1:01 PM Post #4 of 20

ProtegeManiac

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Doesn’t this contradict your statement ? Or you have bad experience using that output? Sorry i am not trying to pick here. As i said i never used that output before. so i have no clue myself.

That's because some integrated amps don't just have a preamp input and output, but also have a direct amp input that bypasses their preamp stage. This is a lot less common now though.
nad-304-755570.jpg



To my understanding once you make the connection like that, the volume is controlled by the pre-amp (in this case Rotel) while the thing that comes after that just gives the power.

Ideally, yes. You're supposed to connect it to an amp that has no preamp section, like this one:
4118571-5951-2__42915.1510822200.jpg

4118571-5951-5__32123.1510822200.jpg


Unfortunately headphone amps don't come as separate preamp and power amp modules. At best you have something like the WooAudio WA6SE and some older AudioGDs that have the power supply on another chassis.


Unfortunately this amp i have does not have a TAPE OUT. Waiting to see your feedback on the pre-out.

Check your integrated amp's manual. If it's possible to set it to do fixed voltage output instead of just variable preamp, then that means it can work as a line out just passing the signal from the source or its DAC as is.

If not then do it the other way around - get a DAC-HPamp and run your sources into that, then run its fixed voltage output to your integrated amp. Right now the only one I know within your budget would be the AudioGD NFB-11 - it has a front switch to select either fixed voltage or variable voltage preamp output.
NFB121.jpg
 
Mar 15, 2018 at 5:08 PM Post #5 of 20

Monsterzero

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I have a similar set-up where I have gone:

PC>Schiit Eitr>Audio GD R2R-11(amp/DAC)>La Figaro 339>Kenwood Eleven GX

So thats 2 headphone amps,a receiver,a dac and its all tied together.
The R2R-11 has variable and fixed input,but since I dont feel like removing the top each time i want to use it I keep it on variable and around 50%

R2R112.jpg


Running a pair of RCAs from the DAC out(shown above)Into the input of the La Figaro 339 connected with a Vampire connector

s-l640.jpg


and then another set of RCAs out to AUX input of my vintage Kenwood Eleven GX.

You might be asking yourself ..."WHY"

The R2R-11 serves as fulltime DAC as well as HP amp for low ohm headphones(like your Focals)
The tube amp drives my high ohm headphones and then my Kenwood drives my AKG K240 sextetts(they sound better from solid state)and a pair of Focal 905 Aria speakers,and a sub-woofer too.

The tube amp does not need to be powered up to pass thru the signal.

Hope this helps.
 
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Mar 15, 2018 at 5:21 PM Post #6 of 20

Monsterzero

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Right now the only one I know within your budget would be the AudioGD NFB-11 - it has a front switch to select either fixed voltage or variable voltage preamp output.

The R2R-11 has the same switch but you need to remove the top and switch the jumper to activate fixed(it ships on variable)
Keeping the volume @50% is quite close to the fixed setting.
 
Mar 16, 2018 at 9:26 AM Post #7 of 20

ProtegeManiac

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The R2R-11 has the same switch but you need to remove the top and switch the jumper to activate fixed(it ships on variable)
Keeping the volume @50% is quite close to the fixed setting.

If he's not going to use it as variable preamp output (his integrated amplifier has no amplifier direct input anyway) then he can leave it on fixed and use it as a DAC or DAC-HPamp.

If he buys a power amp later on he can set it to Variable and then leave it that way.
 
Mar 16, 2018 at 12:32 PM Post #8 of 20

Monsterzero

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Yes,but what im saying is simply flipping the switch on the front panel doesnt work.One must go into the innards of amp/DAC and manually switch it to fixed,which makes headphone listening impossible without switching it back.....Goofy implementation.
 
Mar 17, 2018 at 6:31 PM Post #9 of 20

Naha

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I known you are all good intended and i thank you for your kind advice and support but it looks to me like we are overcomplicating things just a bit.
So I went to both support of Burson and Rotel and asked their opinion. they both adviced to use the Rotel’s preout and use a fix 50% on Burson and use the Rotel’s volume as main volume (this was pretty much aligned with my original thought of pre-out usage) so i tried that and it works ok for me. I also conmected the second Burson in to Bluesound node 2 for comparison and for me for now there does not seem to be much difference other than the fact that the Bluesound seem to be 30% louder when connected directly throug Burson (so when Bluesound is the DAC) then when transiting via Rotel (via Optical, so Rolel is DAC). After asjusting the Rotel’s volume a bit they sound pretty similar pleasing to my ears thoug.
Again thanks a lot for your advice.
 
Mar 18, 2018 at 2:43 AM Post #10 of 20

ProtegeManiac

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I known you are all good intended and i thank you for your kind advice and support but it looks to me like we are overcomplicating things just a bit.
So I went to both support of Burson and Rotel and asked their opinion. they both adviced to use the Rotel’s preout and use a fix 50% on Burson and use the Rotel’s volume as main volume (this was pretty much aligned with my original thought of pre-out usage) so i tried that and it works ok for me. I also conmected the second Burson in to Bluesound node 2 for comparison and for me for now there does not seem to be much difference other than the fact that the Bluesound seem to be 30% louder when connected directly throug Burson (so when Bluesound is the DAC) then when transiting via Rotel (via Optical, so Rolel is DAC). After asjusting the Rotel’s volume a bit they sound pretty similar pleasing to my ears thoug.

If you're not going to do it the right way I'd at least do it the other way around. Leave the Rotel at 50% and pray it's around 2volts, and then use the Burson to control output on the headphones, since you can potentially send in a voltage signal that will get noise and distortion into the Burson's input stage which is designed for 2volts, if you rely on changing the input signal voltage. Tchnically that's what the preamp on the Burson does too when it passes the signal to its output stage, but it's not passing through a preamp input stage after its own preamp pumps up the signal level.
 
Mar 19, 2018 at 5:29 PM Post #11 of 20

Naha

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If you're not going to do it the right way I'd at least do it the other way around. Leave the Rotel at 50% and pray it's around 2volts, and then use the Burson to control output on the headphones, since you can potentially send in a voltage signal that will get noise and distortion into the Burson's input stage which is designed for 2volts, if you rely on changing the input signal voltage. Tchnically that's what the preamp on the Burson does too when it passes the signal to its output stage, but it's not passing through a preamp input stage after its own preamp pumps up the signal level.

Thanks for the suggestion. However I am not sweating too much honestly because Rotel’s preamp out is rated at 1.9V
 
Nov 12, 2018 at 11:28 PM Post #12 of 20

NiceStrongArm

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Thanks for the discussion. Have similar set-up with Rotel RA 1572 with pre-out (1.5V) going to Woo WA6-SE. With Rotel volume at 50%, volume of Woo is set at 50% as well. I assume that volume is current modulated and voltage is fix. Seems fine to start with.
 
Apr 30, 2020 at 11:02 AM Post #13 of 20

ManuCV

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Hi,
Sorry for resurrecting a 2 years old thread. I also have a Rotel RA-1572 and I will receive a headphone amp on Monday. I will connect it to the pre out as Naha and NiceStrongArm, but there was an unanswered question which I am wondering myself as well:

"Having the pre-out connected will i be able to switch and listen to both the B&W speakers (plugged directly into Rotel) and Headphones (one at a time)?"

@NiceStrongArm what is your experience? If the headphone amp is turned off can you listen to the speakers, or do you need to physically unplug the headphone amp from the pre outs?

Thanks.
 
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Apr 30, 2020 at 11:47 AM Post #14 of 20

NiceStrongArm

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Hi,
Sorry for resurrecting a 2 years old thread. I also have a Rotel RA-1572 and I will receive a headphone amp on Monday. I will connect it to the pre out as Naha and NiceStrongArm, but there was an unanswered question which I am wondering myself as well:

"Having the pre-out connected will i be able to switch and listen to both the B&W speakers (plugged directly into Rotel) and Headphones (one at a time)?"

@NiceStrongArm what is your experience? If the headphone amp is turned off can you listen to the speakers, or do you need to physically unplug the headphone amp from the pre outs?

Thanks.
You can turn the speakers on/off no problems with the front A/B speaker switch on the RA 1752. If you have a subwoofer as well, then that will need to be turned on/off manually. That is a reason why I may think about replacing the RA 1572 with separate pre/power amp, where the preamp has a true line/tape out, and I can turn the power amp off (no speaker sound) and still have the full switching capabilities of the preamp.

The headphone pre-amp, you simply power off, and that's it. Even if signal path should go to the headphone amp, with power off, there is nothing amplified. No need to unplug headphones or the unplug the RCA pre-out cables.

One more caveat. Depending on your amp and headphones, the Rotel volume level may need to be quite high. I listen to my speakers at volume 35-40 on Rotel, but for headphone listening with Dan Clark Ether 2 planar, I have to crank up volume to 60-70 on Rotel and on Woo it is at ~50%. So when you switch your speakers back on, remember to turn down the volume again.

Depending a bit on the rest of your set-up, you can take source components and run them through a passive pre-amp, i.e., a switch. I use a Tisbury passive pre-amp with two in three out, which can also be run reversed (three in, two out). Shiit makes a one in two out reversible preamp. Or your headphone amp may have switchable line inputs (the Woo WA 6 SE has two).

So my signal path looks as follows:
TT -> phono stage -> Thisbury "out" -> switch between Woo Line in 1 and Rotel aux in through two of three Tisbury "in"
CD -> Coax 1 in Rotel (for speaker listening) -> Rotel pre-out -> Woo line in 2 (for headphone listening, have to turn sub off manually)
Sonos -> Coax 1 in Rotel ....
Tape deck -> Tuner in Rotel [use aux for TT pre-amp, you could use any of the line-ins for any of the line level connections]. I could also run the Tape through the second Tisbury in and then switch between Woo and Rotel on the Tisbury. Don't have a long enough RCA interconnect, and don't use the Tape deck that much, so went the way I described. For Coax input (to use the better DAC in the Rotel compared to the Sonos connect or my old Marantz CD player) I have to go through the Rotel. With a possible new pre/power amp, I may also thinking of adding a separate DAC component.

Hope that helps.
 
Apr 30, 2020 at 12:11 PM Post #15 of 20

ManuCV

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It does help, many thanks. My setup is simpler than yours and I have no subwoofer, so the pre out will do fine.
Thanks for the tip regarding the volume, once I receive the headphone amp (SMSL SP200) I will check if I need to crank the volume up so much. My headphones are quite easy to drive (Hifiman HE400i, B&O H6) and the SP200 is very powerful, so probably it won't be necessary but let's see.

I am also thinking about selling the Rotel and getting separates (preamp + 2 class D monoblocks), but for the time being I am doing fine with the Rotel + B&W 703 - really like this sound.
 

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