SGM8262 and Similar Op-Amps: Benefit or Drawback for IEM Use?

[norinorio]

Hi everyone,

I'm not very knowledgeable about electronics, but I'm currently looking for a dongle DAC to drive my IEMs.

After reading jkim’s posts about the CS431xx distortion issue, I’m thinking of avoiding CS431xx-based models unless the problem has been properly addressed.

I’ve noticed that some dongles include op-amps such as the SGM8262.

My question is:

Are these op-amps actually necessary for driving low‑impedance IEMs, or do they mainly add noise and distortion?

If anyone has specific recommendations for clean‑measuring dongles suitable for IEMs, I would really appreciate it.

Thanks.

 

[DVDdoug]

The Apple Dongle got an excellent review. (I don't own one and I don't use IEMs.)

I would look at the specs/measurements rather than what chips are inside.

An op-amp (or other analog circuitry) isn't going to fix DAC distortion. As far as I know that distortion isn't audible, although it's measurable. Most DACs (most electronics, actually) are better than human hearing although with a headphone amp you need enough power to drive your particular headphones/IEMs as loud as you want without overdriving it into audible distortion.

Are these op-amps actually necessary for driving low‑impedance IEMs, or do they mainly add noise and distortion?

"Regular" op-amps can't directly drive low-impedance loads. The SGM8262 seems to be a special chip. There are lots of specialized audio chips or a "current booster" stage can be added to an op-amp. Decades ago, I built a headphone amp from a chip that was intended as a low-power (2-Watt?) power amplifier chip.

 

[norinorio]

Actually, I’ve been using the Lightning variant of the Apple dongle in my car, and it works great.

Since I recently switched to Android, I was considering getting the USB‑C Apple dongle as well, but I noticed it listed in jkim’s spreadsheet, so I started looking for alternatives instead.

 

[Weastony]

На самом деле, я использую в своей машине адаптер Apple с разъемом Lightning, и он отлично работает.

Поскольку я недавно перешёл на Android, я подумывал о приобретении USB-C адаптера от Apple, но заметил его в таблице jkim, поэтому начал искать альтернативы.

I think the JM20 without OP would be the best choice in this form factor.

 

[norinorio]

I have some budget to spare, so I’m also interested in 4.4 mm support.

Is it actually worth it, or just snake oil?

 

[staticV3]

I have some budget to spare, so I’m also interested in 4.4 mm support.

Is it actually worth it, or just snake oil?

4.4mm output makes no sense for IEMs.

Maximum output voltage is increased, but the 2V that you get with 3.5mm is already excessive for IEMs.

The trade-off for that is increased noise, which unlike the increased voltage can affect the experience audibly in the form of hiss.

 

[norinorio]

I went with the JM20.
Thank you for the advice.