Reddit mentions of LyxPro STP10 Compact 4 Channel Headphone Amplifier 1/4" and 3.5mm (Mini 1/8") Stereo Mono & RCA Inputs, Clean Amplifier Circuit, Power On LED, for Home & Studio

SR225i (they're a generation old, I believe)

This amp.

Absolutely worth it, IMO. I also have a pair of DT770s I'm about to try out that I think will really see performance improvement as well. My Grados are for music and my Beyerdynamics are for movies/gaming/wearing for long periods of time.

I have a 3.5mm to RCA cable into my headphone amp which also has an RCA pass through and that goes to my speakers.

However, I don't know if you want to spend the money on a headphone amp with a pass through, so I guess you could buy a cheap headphone splitter cable with one connected to your headphones and another to your speakers.

I guess that could cause issues with volume control since your headphones would be at full blast a lot if you have your computer volume turned up. You could also consider buying an audio selector or something of the sort.

EDIT: You can see something like this: http://www.sweetwater.com/store/detail/SplitMix4?adpos=1o2&creative=55674776881&device=m&matchtype=&network=g&gclid=Cj0KEQiA_fy0BRCwiLaQ5-iFgpwBEiQA884sOU1j7B-NS0xIsjfFn5cl6zqWVn6QW29yCAlxxFbHP5gaAs6q8P8HAQ

I've never ordered from this website, but I have a product from the manufacturer and they make quality stuff.

EDIT 2: Here's an amazon link with Prime if you prefer.

($50) http://www.amazon.com/ART-SPLITMix4-4-Channel-Passive-Splitter/dp/B002VX0DCE

You could also consider this product for like half the price: ($26) http://www.amazon.com/gp/aw/d/B00X4SSVAG/ref=mp_s_a_1_9?qid=1453346171&sr=8-9&pi=AC_SX220_SY330_FMwebp_QL65&keywords=Stereo+input+splitter
Just be sure to buy an audio adapter to send the audio from the splitter to your speakers.

EDIT 3: Spamming you again with another link to another product. ($19) http://www.amazon.com/gp/aw/d/B003M8NVFS/ref=pd_aw_sim_23_2?ie=UTF8&dpID=412WWEsRYzL&dpSrc=sims&preST=_AC_UL100_SR100%2C100_&refRID=0RJSQ3JMS6FC9YTJ55GZ



TL;DR - All of these products will get the job done. Just pick which one you want. 👍

Specs for you.

Image #9 shows my LyxPro STP10. It takes sound from the DAC in the next picture, and (a) amplifies it, and (b) duplicates it to 4 outputs. That way, friends can plug in if we play a game together (I stream on Twitch), watch movies at our own comfortable volumes, etc. Just makes things all around easier.

Got it! Thanks again for your help. Do you think one of these will work? Again, thanks a ton for your help!

LyxPro: says Output Impedance: Minimum 10Ω Per Channel
https://www.amazon.com/LyxPro-Compact-Channel-Headphone-Amplifier/dp/B00X4SSVAG/ref=sr_1_6?s=electronics&ie=UTF8&qid=1495752891&sr=1-6&keywords=headphone+amp&refinements=p_72%3A1248879011

or

FiiO-E12A: found a site that says Output Impedance : < 0.3 Ω
https://www.amazon.com/FiiO-E12A-Portable-Headphone-Titanium/dp/B00IM6WPHU