Attenuation T-pad after minidsp help

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Hi All,

I have been working on setting up a recently finished pair of open baffles using a minidsp (unbalanced). Unfortunately the minidsp is generating audible noise and surfing the web has not brought a structural solution.

But, one idea I found might work but in order to try that I need some help:
By using a T pad attenuator I may be able to attenuate the noise right after the minidsp. Now I have been studying on how to come to the right resistor values but somehow I am not doing it right and am confuse about Z1 and Z2.
(I have no electronical background).

My setup line is as follows:
Audio PC to TEAC UD-501 DAC to MiniDSP (X-over at 450hz) into my Melody tube amp for the left and right high and mids into a Tangband W-1808 (8 Ohm)
And from minidsp low into a Hypex DS4.0 plate to double Emminence Alpha15a (4 Ohm) with one amp per channel.

Mini DSP input 6 KOhm Output 560 Ohm
Melody MI880 input 250 KOhm Output 8 and 4 Ohm (8 Ohm used for the Tangband)
Hypex DS4.0 input 10 Ohm. Output 8 and 4 Ohm (4 Ohm used per double Alpha15a)
I am guessing that attenuation of 10dB should be ok to remove the audible noise (or 6 dB?) Noise in the Tangbands is a high frequency tone and the Alpha more of a lower white noise.

The results of my online T pad calculators haven't made any sense so please help me with calculating the right resistors for both the Mid-High and the Low outputs right after the minidsp.
Or please advise me if this idea isn't a good one

Thank you,
Jock
 

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