[lambdastorm]

First if you have your A-100 with the resistors bypassed (jumpers engaged) then this is the wrong setting for high efficiency IEM.
As for the ground, have you tried the RCA ground loop isolator? They are between 7 and 10 bucks and are designed to get rid of of a ground loop buzz.
Search Amazon for ground loop isolator and youll find quite a bit
They look like this

I haven't looked into groundloop isolator yet, will try it once I get back to the US.

I get a few keks out of the IEM thing. My bad for not explaining. The ifi DAC I mentioned is a Micro iDSD BL, it has a mighty powerful headphone amp built-in and I use it for all headphones that gets too loud on the A100, including my trusty IEMs.

 

[owatito]

Absolutely...

The HD650 is 300 Ohms, so it's perfectly safe to run them on the A-100 with or without the jumpers.

Hello KeithEmo, I think this product is fantastic, how safe is it with the akg k712 pro? (62 ohms), taking into account that the jumpers would be connected. I have a Akg k340 electrostatic-dynamic, with 400 ohms, according to the same AKG, were recommend connected directly to a speaker amplifier, I am very curious how they can sound on the A-100.

I'm sorry for my bad English.

Greetings.

 

[KeithEmo]

Any questions of safety are actually quite simple - but they can still be confusing.

The power going to the headphones is coming from the output of a very powerful amplifier designed to power speakers.
With the jumpers OUT, there is a 220 Ohm resistor connected between the output of the amplifier and the headphone.
With the jumpers IN, the output of the amp is connected directly to the headphones.

First off, with any headphones whose manufacturer recommends connecting them directly to a speaker amplifier, JUMPERS IN is the best option, and is perfectly safe.
With the JUMPERS IN you are connecting the headphones directly to the amplifier - as recommended.
(Of course, you do still need to exercise some care.... it would be possible to burn out any headphone if you turn the amp up too far - but your ears will probably be bleeding long before then.)

With other headphones, how the jumpers act will depend on the impedance of the headphones.

For example, if you have 300 Ohm headphones, the 220 Ohm resistor reduces the voltage reaching the headphones by about 40%.
These headphones require a relatively high drive voltage, so they'll work well on the A-100, and they'll only be a little bit louder if you install the jumpers (something like 2 dB louder).

HOWEVER, the lower the impedance of your headphones, the more effect the resistor will have.
For example, with 62 Ohm headphones...... the resistor in the A-100 will have a much more significant effect.
With 62 Ohm headphones, and with the A-100 playing at the same loudness, the headphones will receive 16 TIMES as much power with the JUMPERS IN as with the JUMPERS OUT.
This isn't specifically dangerous, but it means that you will have to set the volume on the A-100 MUCH lower with the jumpers in to reach similar loudness.
It also means that, if your 60 Ohm headphones were playing loudly without the jumper, by putting in the jumper you might risk burning them out - or hurting your ears.
It also means that, depending on the level of your signal source, and the efficiency of your headphones, the noise floor of the A-100 might be audible, and you might simply have trouble adjusting the volume control carefully enough.

The main danger is that, WITH THE JUMPERS IN, if you set the A-100 to play at a comfortable level with high impedance headphones, and you then plug in low impedance ones without adjusting anything, they will be VERY LOUD.

In your case, the A-100 will work great with your k340's with the JUMPERS IN (and probably won't work very well with the jumpers out).
It will also work great with your K712's with the jumper OUT.
However, with the jumpers IN, you might notice some noise with the K712's, and you may barely be able to move the volume control before they get really loud.

But the big DANGER is that, if you have the JUMPERS IN, and you're playing the A-100 with the k340's, then you plug in the k712's without remembering to turn the A-100 all the way down first, you may fry the K712's.

Hello KeithEmo, I think this product is fantastic, how safe is it with the akg k712 pro? (62 ohms), taking into account that the jumpers would be connected. I have a Akg k340 electrostatic-dynamic, with 400 ohms, according to the same AKG, were recommend connected directly to a speaker amplifier, I am very curious how they can sound on the A-100.

I'm sorry for my bad English.

Greetings.

 

[owatito]

Any questions of safety are actually quite simple - but they can still be confusing.

The power going to the headphones is coming from the output of a very powerful amplifier designed to power speakers.
With the jumpers OUT, there is a 220 Ohm resistor connected between the output of the amplifier and the headphone.
With the jumpers IN, the output of the amp is connected directly to the headphones.

First off, with any headphones whose manufacturer recommends connecting them directly to a speaker amplifier, JUMPERS IN is the best option, and is perfectly safe.
With the JUMPERS IN you are connecting the headphones directly to the amplifier - as recommended.
(Of course, you do still need to exercise some care.... it would be possible to burn out any headphone if you turn the amp up too far - but your ears will probably be bleeding long before then.)

With other headphones, how the jumpers act will depend on the impedance of the headphones.

For example, if you have 300 Ohm headphones, the 220 Ohm resistor reduces the voltage reaching the headphones by about 40%.
These headphones require a relatively high drive voltage, so they'll work well on the A-100, and they'll only be a little bit louder if you install the jumpers (something like 2 dB louder).

HOWEVER, the lower the impedance of your headphones, the more effect the resistor will have.
For example, with 62 Ohm headphones...... the resistor in the A-100 will have a much more significant effect.
With 62 Ohm headphones, and with the A-100 playing at the same loudness, the headphones will receive 16 TIMES as much power with the JUMPERS IN as with the JUMPERS OUT.
This isn't specifically dangerous, but it means that you will have to set the volume on the A-100 MUCH lower with the jumpers in to reach similar loudness.
It also means that, if your 60 Ohm headphones were playing loudly without the jumper, by putting in the jumper you might risk burning them out - or hurting your ears.
It also means that, depending on the level of your signal source, and the efficiency of your headphones, the noise floor of the A-100 might be audible, and you might simply have trouble adjusting the volume control carefully enough.

The main danger is that, WITH THE JUMPERS IN, if you set the A-100 to play at a comfortable level with high impedance headphones, and you then plug in low impedance ones without adjusting anything, they will be VERY LOUD.

In your case, the A-100 will work great with your k340's with the JUMPERS IN (and probably won't work very well with the jumpers out).
It will also work great with your K712's with the jumper OUT.
However, with the jumpers IN, you might notice some noise with the K712's, and you may barely be able to move the volume control before they get really loud.

But the big DANGER is that, if you have the JUMPERS IN, and you're playing the A-100 with the k340's, then you plug in the k712's without remembering to turn the A-100 all the way down first, you may fry the K712's.

Wonderful and very interesting explanation, thank you very much for your time to answer my question, I am very clear that I must and should not do with my headphones.

Excellent day KeithEmo

 

[Th3Drizzl3]

hey keithemo any ballpark timeframe for that new model? I'm hanging onto my a100 until then of course but I'm curious

 

[PopZeus]

Love this amp paired with the Elac UB5.

 

[Namtar]

I couldn't take it anymore. Just ordered my A100 from Emotiva.
Tentative setup will be PC -> Marantz SR7100 (sadly I have to use 3.5mm to RCA instead of Optical out - the receiver won't act as a DAC and output analog from a digital source) -> A100 for headphones. The receiver will be the preamp so I can have some volume control on the A100.

The main headphones will be my Massdrop HE-4XX.
And now my wife can get the Magni 2U when she decides to go for good headphones instead of her gaming headset!

I'll post back with comparisons between the A100 & Marantz headphone jack when I'm able.

 

[garbulky]

I couldn't take it anymore. Just ordered my A100 from Emotiva.
Tentative setup will be PC -> Marantz SR7100 (sadly I have to use 3.5mm to RCA instead of Optical out - the receiver won't act as a DAC and output analog from a digital source) -> A100 for headphones. The receiver will be the preamp so I can have some volume control on the A100.

The main headphones will be my Massdrop HE-4XX.
And now my wife can get the Magni 2U when she decides to go for good headphones instead of her gaming headset!

I'll post back with comparisons between the A100 & Marantz headphone jack when I'm able.

Go get you a cheap USB DAC! You'll thank yourself. You can have them for between $30 and $100

 

[Namtar]

Go get you a cheap USB DAC! You'll thank yourself. You can have them for between $30 and $100

I'm still unsure if I'm going to go the USB route - I've had bad luck with them in the past. I'm honestly good with 24/96 coming from the PC out since I'm sure most of the video games I play aren't using audio mastered in anything higher.
Long term I'm going to probably save up for a bit and get a Topping D50 - or I might go all out and get the DX7s so that later on I can go balanced as I get back into the headphone / audio game. Regardless of what I choose, I want my DAC to have volume control so it can act as a preamp. (and long term balanced headphone amp will be something along the lines of a Mojo2

 

[Mightygrey]

I'm still unsure if I'm going to go the USB route - I've had bad luck with them in the past. I'm honestly good with 24/96 coming from the PC out since I'm sure most of the video games I play aren't using audio mastered in anything higher.
Long term I'm going to probably save up for a bit and get a Topping D50 - or I might go all out and get the DX7s so that later on I can go balanced as I get back into the headphone / audio game. Regardless of what I choose, I want my DAC to have volume control so it can act as a preamp. (and long term balanced headphone amp will be something along the lines of a Mojo2

Emotiva have been threatening to release a DC-2 balanced dac soon that ought to do many of these things...

 

[Namtar]

First impressions are VERY positive. Listening to some of my "usual" youtube music - the bass on my headphones has really tightened up and it's not muddy. This amp exercises a LOT of control over my cans.

 

[garbulky]

First impressions are VERY positive. Listening to some of my "usual" youtube music - the bass on my headphones has really tightened up and it's not muddy. This amp exercises a LOT of control over my cans.

You might like this DAC. A cheap low cost alternative to an in built sound card.
Behringer UCA 202. $30

 

[bequietjk]

Super tempted in grabbing up this A-100. I remember when the Mini-X was out and I was drooling over it's passive speaker/headphone capability. Plus the overall build of the amp looks super clean, especially the blue ring.

 

[Rchandra]

So I just purchased my unit and I have a ton of background noise with jumpers installed using my hd800S and focal elears. It's such a great amp but the noise floor is ridiculous. Now I see some people saying their is no background noise and some like me saying their clearly is. Has anyone been able to get rid of that background hiss?

 

[Baten]

So I just purchased my unit and I have a ton of background noise with jumpers installed using my hd800S and focal elears. It's such a great amp but the noise floor is ridiculous. Now I see some people saying their is no background noise and some like me saying their clearly is. Has anyone been able to get rid of that background hiss?

I fear it's unit to unit variance not unexpected in this $220 price range :/