Help with connections please

[redchiro67]

Hi to all,
I am a little unsure of the best way to connect 3 components:
1. SMSL DO300 DAC
2. Topping L70 Headphone Amplifier
3. SMSL AO200ii (integrated) amplifier
All 3 components are balanced. The inputs for the L70 can be balanced or single-ended. The inputs on the AO200ii speaker can be balanced or single ended. The DO300 DAC outputs balanced or single-ended.
The confusing part is all 3 units can be pre-amps.
I am only using this old school with a Sony DVP-S9000ES DVD/CD/SACD unit connected via coax to the SMSL DAC. This unit also has RCA out if I want to listen to an SACD. Those are connected to the L70 RCA input.
My main use is as a bedroom system for headphone use. That's why I got the L70, for remote control. I relax on the bed about 12 feet away. I have Sennheiser HD650 single-ended for now because my extension cord is single-ended.
I have a small set of speakers, ERA Design 4 for background music. Right now, the input to the SMSL AO200ii is the single-ended RCA from the DO300 DAC. So, I can't play SACD through speakers because coax digital is feeding the DAC. SACD is only analogue.
The Sony is feeding the L70 through it's RCA out and my DAC is connected via balanced XLR to the L70 as well. I can switch btw XLR and RCA on the L70 and thus, listen to CD or SACD via headphones.
Currently, the SMSL DO300 DAC is set at fixed output.
There is the availability to connect via XLR from the output of the L70 to the balanced XLR input of the AO200 mkii. I would have to buy another set of XLR cables and I am not sure if that connection would bring SACD as well as CD to the speakers? Then I could disconnect the RCA from the DAC to the AO200??????
Questions:
1. Suggest best way to connect these 3 components for mainly headphone listening but I do have speakers and the amp to drive them.
2. All of these components have preamp capability and that is confusing me.
3. Right now, the DAC is fixed output. Connected via balanced to L70. Is that the best if my priority is headphones?
4. I could buy another set of XLR and run it from the L70 out to the AO200. Worth it?
5. I was considering a set of balanced cables for my 650's. But then I run into the problem of length. I need about 20 feet from the L70 to my head. The only place I could find a balanced extension was Hart cables. It was not cheap and that is added to the cost of the balanced cable for the 650. So what do people do with a balanced headphone rig that is not for desktop? Do they get a separate cable about 6-10 feet for the phones and a separate extension to reach the amp or a single very long balanced cable for the headphones, eliminating the need for an extension cable?
This is all a bit confusing because of the choice of balanced vs RCA and the fact that all 3 components can be used as pre-amps.
6. My last thought was returning the AO 200ii integrated amp and getting the Fosi monoblocks which have no pre-amp circuit. I could then use either the L70 or DO300 DAC as the volume/pre-amp.
My head is spinning a bit here. Thanks to all

 

[NTK]

Questions:
1. Suggest best way to connect these 3 components for mainly headphone listening but I do have speakers and the amp to drive them.
2. All of these components have preamp capability and that is confusing me.
3. Right now, the DAC is fixed output. Connected via balanced to L70. Is that the best if my priority is headphones?
4. I could buy another set of XLR and run it from the L70 out to the AO200. Worth it?
5. I was considering a set of balanced cables for my 650's. But then I run into the problem of length. I need about 20 feet from the L70 to my head. The only place I could find a balanced extension was Hart cables. It was not cheap and that is added to the cost of the balanced cable for the 650. So what do people do with a balanced headphone rig that is not for desktop? Do they get a separate cable about 6-10 feet for the phones and a separate extension to reach the amp or a single very long balanced cable for the headphones, eliminating the need for an extension cable?
This is all a bit confusing because of the choice of balanced vs RCA and the fact that all 3 components can be used as pre-amps.
6. My last thought was returning the AO 200ii integrated amp and getting the Fosi monoblocks which have no pre-amp circuit. I could then use either the L70 or DO300 DAC as the volume/pre-amp.

1,2,3:
IMHO the easiest way is: DAC → L70 → AO200 using all balanced connections. The "pre-amp" capability is basically you can control the volume using any of the 3 components (when you don't use the Bluetooth of the AO200 and its tone controls). You shouldn't need to feel confused.
Putting the DAC in fixed output mode is a correct move.
I think the easiest way is to control the volume using the L70. Set the volume on the AO200 so that when you switch from headphones to speakers, the volume levels are what you like (i.e. when you are playing your headphones "loud", and you switch to speakers, the speakers sound similarly "loud"). Fix the volume level of the AO300 at that level and use the L70's volume knob for volume adjustments for normal use.

4.
That would be my preference. See above. Keep the SACD digital coax connection to the DO300 DAC, and the RCA connection to the L70.

5.
There is really no benefit to using balanced cables for your HD650's. The benefit of balanced headphone connections is only for headphone dongles powered by USB driving insensitive headphones (and a negligible improvement in crosstalk). Since you have a L70 desktop amp, that is not an issue.
Headphone connections are different from line level signal connections (e.g. between a DAC and an amp). There is no ground loop problem (with the headphones and the amp), and noise pickup is also not an issue because of the low impedances in the amp output and headphones.

6.
Or you can simply set the appropriate volume setting for the AO300, keep it fixed, and then forget about it.

 

[redchiro67]

Fantastic explanation, one and done! I will grab another set of short XLR cables and try the system connected like this. Just was trying to avoid redundant pre-amp circuits which is what had me scratching my head a bit.
Guess your reasoning for using l70 for all volume changes is too keep everything consistent. Makes sense. I probably would have used the volume on the AO200.
Thanks again and thanks for suffering through the long post, ha, ha. I didn't realize how long it was until I actually submitted it. Was planning to edit it down.