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How to split stereo into stereo plus sub out?

Consider a budget system that plays HD music files from a PC using either USB or Aptx HD Bluetooth. If I am using a DAC similar to the SMSL M400 or Topping D90SE and it is connected to a Yamaha P7000S amp which powers a L and R speaker, what is the best way to add dual powered subwoofers?
I own two SB-2000 subwoofers, but I am not sure how to connect them into the system above because the amp doesn't have any sub-out or pre- outputs of any type.

I have not purchased the SMSL M400 yet, but none of the devices in its class have subwoofer outputs (as far as I have seen).
Without spending a lot of money, how should I connect my two powered subwoofers into this system? Thank you.
lowoverdrive
millercarbon's avatar
millercarbon
12,531 posts
 
Two ways, both equally good, one free the other maybe $20 tops.  

The free way is if your powered subs have speaker level inputs. Simply connect the subs to the amp speaker outputs.    

The $20 way is to use what is called a Line Out Converter. The LOC is nothing more than a couple resistors, typically 20k to 50k Ohm, that drop speaker level voltage down to line level. If you do this buy the cheapest one you can find, unless you care about how it looks because that is all you are paying for, a better looking box and RCA.  

The third option for about $5 you probably won't want to do as it calls for some soldering. Basically you build your own LOC using your own resistors and connectors. Here is the interweb's best tutorial on the subject, in case you really want to understand what is going on.  https://www.epanorama.net/circuits/speaker_to_line.html/  

Here is my system page where you can see a photo of the LOC mod that I did to my Melody integrated following the info in the epanorama article https://systems.audiogon.com/systems/8367
lowoverdrive OP
169 posts
 
Here is my system page where you can see a photo of the LOC mod that I did ...
That's an amazing looking system! Wow.
In regard to the free way and the $20 way, my amp only has outputs for 2 speakers. I'm using banana plugs and good quality speaker wire.

I assume I need to make some splitter cables so I can connect both the existing speakers and the LOC to the same output from my amp.

I don't know enough to ask the right question, but it seems that I should be concerned about impedance or other similar issues if I put a splitter in the system. Is that true?
fuzztone's avatar
fuzztone
5,591 posts
 
For free.

Connect the speakers to the speaker outs on the sub.  

millercarbon's avatar
millercarbon
12,531 posts
 
You do not need a splitter. Connect the LOC to whichever speaker outs you want. At 20k (or more) the LOC presents near zero load to the amp. It will not affect anything. Also the bass being used to drive the subs is so low it is not even stereo. So you could if you wanted connect all the subs to just one channel.  

You are right to be thinking about impedance however at 20k ohms or even higher it simply is not a factor.
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