Conrad Johnson ET3se connected to a subwoofer

I couldn't find an input impedance spec on your subwoofer, but it appears that both the ET3se and the DAC2 D have low output impedances, and the input impedance of your power amp is a fairly high 47.5K. Given that, and given that the DAC2 D provides a 32-bit digital volume control, and assuming that the sub does not provide speaker level inputs, three methods seem reasonable, and all are probably worth trying and comparing:

1)As you indicated, you can connect the second pair of RCA outputs provided on the DAC to the sub. You would control the volume of the system with the DAC, and leave the preamp's volume control at a fixed setting. It may be best to choose a fixed setting of that control such that the volume control of the DAC is used in the upper part of its range, although some experimentation with several combinations of the two settings may be worthwhile.

2)Use a pair of splitters or y-adapters at the output of the CJ preamp, such as a pair of these. If the length of the cables to either the sub or the power amp is particularly long, it would be best to choose a low capacitance cable (e.g., say 20 or 25 pf/foot or less) for the long run(s).

3)Eliminate the preamp altogether, and drive both the sub and the power amp with the DAC.

There is a slight possibility with any of these approaches that ground loop-related hum could result, but chances are you'll be fine in that respect regardless of which method is chosen.

Finally, if you are using just one sub, as appears to be the case, I'm assuming that it provides separate inputs for the left and right channels, rather than just a single input that is intended to receive a mono signal. Post back if that is not the case.

Regards,
-- Al

Thanks Almarg for your responses.

I will try 1st and 2nd method this week-end.

With the 2nd method, do you think that it will degrade the sound using the Y-adapters ?

I won't go with method no 3 since I just buy the ET3 and intend to use it.

Yes I'm using only one sub and it has separate inputs for the left and right channels (only low-level, no high-level I/O)

My speakers are Totem model 1 signature and they will need a sub for low frequencies.

With the 2nd method, do you think that it will degrade the sound using the Y-adapters?

I suspect that it will not in this specific case, considering the specific impedances that are involved (and assuming that ground loop hum does not occur, which is unlikely but doesn't have much predictability).

From a technical standpoint, I would expect that adverse effects people sometimes report as a result of introducing splitters or y-adapters into the signal path are in most cases the result of the inability of the component driving the cables to simultaneously drive two sets of cables and the two specific load impedances with good results. Rather than being caused by the splitter or y-adapter itself.

Good luck. Regards,
-- Al

Thanks Al

Hi Al, I have tried method 1, I set the volume of the ET3 at 50 and the DAC at 11 o'clock, the sound is good but the bass is very strong.

With method 1, I don't know if the sound was reproduced mostly by the ET3 preamp or the preamp of the DAC2.

I've ordered the Y adapter at Take Five Audio, will try the method 2 when I receive the adapter.

I'm thinking if I sell the Totem Model 1 Sig and the sub and buy the more powerfull speakers like the Harbeth c7es3 so I won't need a Sub anymore

If you are looking for a speaker with powerfull bass forget about the C7. I owned them and thought that they lacked in the bass. As a matter of fact I have the smaller P3ESR and I think the bass on them is way better .