[giorgos236]

I have my HD660s connected to the Drop THX 789. Sound is great, however I wish it would get louder using the 1/4 in connector. If I buy an adapter and use the XLR output on the THX using the existing unbalanced cable would the volume increase? Not looking for a quality improvement, just increase in volume.

The pads seems to be in ok shape, would it make a difference if I change them? If yes, what should I go for that is reasonably priced.

[Yes, I am old and like loud music...]. Thanks.

 

[Roseval]

If I buy an adapter and use the XLR output on the THX using the existing unbalanced cable would the volume increase?

No, it will decrease as you probably blow the amp.
What you need is a "balanced" cable for the HD660.
This will double the output power

 

[giorgos236]

No, it will decrease as you probably blow the amp.
What you need is a "balanced" cable for the HD660.
This will double the output power

Any suggestions for a good balanced cable that is reasonably priced? I am not sure i should trust ebay.

 

[PurpleAngel]

Any suggestions for a good balanced cable that is reasonably priced? I am not sure i should trust ebay.

I trust eBay, at least for cables.
Here is a cable that I bought for my HD58X, which should work fine with the HD660s.

 

[gimmeheadroom]

It's not a balanced amp. Using an XLR cable won't even get you more power.

 

[CoryGillmore]

deleted for misinformation...

 

[Roseval]

According to https://drop.com/buy/drop-thx-aaa-789-linear-amplifier
This are the 2 headphone outs

Balanced Output

• Output power: 6000 mW, 16 ohms, <1% THD (watts per channel)

Single-Ended Output

• Output power: 3000 mW, 16 ohms, <1% THD (watts per channel)

It's not a balanced amp. Using an XLR cable won't even get you more power.

What they called a balanced connection in the headphone world has nothing to do with balanced as we know it.
Instead of a TRS they use a TRRS enabling us to connect our headphone just like our speakers to a amp (4 wires instead of 2 + common ground).
By it self this does nothing at the headphone side but do allow design like push/pull, floating ground, etc at the amp side.

Likewise you will find many DAC's having single ended out and XLR out (talking line out here) with the RCA output producing approx 2 V and the XLR 4.2 V without using a balanced desing internally.
In fact most pro gear is single ended by design but does have balanced out..

 

[gimmeheadroom]

Thanks for the link. I'm not really sure I trust drop to get anything right but what was more interesting was the full power THD rating of < 1% whatever that means. They quote THD and THD+N at low output levels (1mW, 100mW) which look very good. I wonder if the distortion is non-linear and gets back quickly at some point.

 

[Law87]

how is it possible that your ears are not damaged? THX 789 have enough power for susvara...

 

[gimmeheadroom]

how is it possible that your ears are not damaged? THX 789 have enough power for susvara...

I think that is a good question. I suspect his amp is not being driven correctly or properly. The output at 150 ohms should be enough to set his 660Ss on fire.

 

[giorgos236]

The thx gets pretty loud without the XLR connection but i could use a little bit more power for a few minutes at a time.
Can anyone with the thx 789 please confirm that the XLR output is stronger? Thanks.

 

[gimmeheadroom]

The thx gets pretty loud without the XLR connection but i could use a little bit more power for a few minutes at a time.
Can anyone with the thx 789 please confirm that the XLR output is stronger? Thanks.

On paper anyway, with that amp and headphones you are out of runway very quickly. XLR is not going to help no matter what.

What are you using for a source?

 

[CoryGillmore]

According to https://drop.com/buy/drop-thx-aaa-789-linear-amplifier
This are the 2 headphone outs

Balanced Output

• Output power: 6000 mW, 16 ohms, <1% THD (watts per channel)

Single-Ended Output

• Output power: 3000 mW, 16 ohms, <1% THD (watts per channel)

What they called a balanced connection in the headphone world has nothing to do with balanced as we know it.
Instead of a TRS they use a TRRS enabling us to connect our headphone just like our speakers to a amp (4 wires instead of 2 + common ground).
By it self this does nothing at the headphone side but do allow design like push/pull, floating ground, etc at the amp side.

Likewise you will find many DAC's having single ended out and XLR out (talking line out here) with the RCA output producing approx 2 V and the XLR 4.2 V without using a balanced desing internally.
In fact most pro gear is single ended by design but does have balanced out..

You’re right it’s the SMSL that has the identical outputs for SE and XLR.

 

[Roseval]

I wonder if the distortion is non-linear and gets back quickly at some point.

It drops when playing louder up to a certain point. From there it rises very steep
https://www.audiosciencereview.com/...easurements-of-massdrop-thx-aaa-789-amp.5001/

 

[gimmeheadroom]

You’re right it’s the SMSL that has the identical outputs for SE and XLR.

This issue came up in a few threads recently and everybody said the Drop and monoprice THX amps aren't balanced. I don't understand how the XLR connector changes anything. Confusing...