Which Connection? Phono / XLR / Optical / Coax / HRS (Harman HK990 / HD990)


Active Member
Which Connection? Phono / XLR / Optical / Coax / HRS (Harman HK990 / HD990)

I’ve just become the proud owner of the Harman HK990 / HD990 after many weeks/months listening to a vast amount of hi-fi (which I quite enjoyed tbh).

I wanted something to replace my trusty Kenwood, which I have struggled with, especially trying to get a warm powerful sound.

I nearly ended up with a hybrid value/transformer amp which sounded lovely, very very smooth and a natural warm sound with perfect detailing. If you want a smooth sounding powerful system then I highly recommend the Synthesis Magnum.

The Harman was close, but with the added features it just swung it for me.

There are not many things I’ve come across that have exceeded my expectations, but this pair have really come to life at home, sounding much better than in the show room.

But anyway….

Due the amount of features these units have there is a myriad of connection possibilities.
1) Analogue Phono
2) Analogue Balanced XLR
3) Digital Optical
4) Digital Coax
5) HRS (High-Resolution Synchronization) (Analogue/Digital?)

I’ve so far listened to:
HRS – sounded very weak. Lacked life, too bright, reduced imaging.
Analogue Phono – warm smooth sound, detailed with very good imaging.
Digital Coax – more detailed, very controlled with exceptional imaging. Instruments very very separated but can sometimes sound a little too clinical with percussion sounding a little harsh occasionally.

I haven’t tried Optical or XLRs yet. So far I prefer the old fashioned phono’s so is it worth me getting a pair of XLRs and do I assume there is no benefit in trying optical over coax?

And what are the benefits of XLRs?

Thank you for the help.

If I can especially recommend Audio Images in Lowestoft who were fabulous.



Active Member

I take it you are using the room EQ capabilities of the HK990? If you are, then the amp will be digitising the input prior to processing, so there is little point using the analogue connections as you will be adding another step to the chain.

CD (digital, converted to analogue) > analogue link > Amp (converted to digital, processed, turned back to analogue)

Much better to go

CD (digital) > digital link > Amp ( processed, turned into analogue)

In prinicple, the best digital link should be the HRS system which uses a master clock in the Amp to avoid jitter in the S/PDIF link (optical or coax). This should be a better version of the optical or coax digital link.

Ultimately, you should go with whatever link you prefer, but the link that has the greatest chance of success is the HRS link.


Active Member
Hi Andy, thanks.

Yes you are correct, although I am not/have not used the EQ yet, so guess the amp is not converting back & forth, just straight through.

CD (DAC) > analogue link > Amp (AtA)

This sounded a little crisper.
CD (digital) > digital coax > Amp (processed, turned into analogue)

HRS – very poor?!?!

Sound is very persona/subjective and we're all different, but I didn't know if its worth getting a set of XLR's, especially as I'm favoring the phono's at the moment which is giving a slightly warmer sound?


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