SMSL 98E killed my setup?


So today I got the SMSL SA-98E amp from amazon after waiting for 50 days. I was pretty excited since I could finally test out my new passive speakers. My setup up to then was a scarlet solo and a jds atom amp to drive my HD600s. So I unplugged my headphones, connected the rca outputs from the atom into the rca inputs of the smsl, and hooked the speakers to the smsl. When I tried to play music, the speakers made a high pitched buzzing sound not too different from a sine wave, and there was no hearable trace of the music I was trying to play. I started troubleshooting, rechecking the speaker cables were connected properly etc. I noticed that the buzz became much quieter when I unplugged the rca inputs of the smsl, and upon reconnecting said inputs, the speakers made a very loud sound like when you touch a live guitar cable; I immediately turned the smsl off, but the atom amp and the scarlet solo didn't survive the ordeal. Their lights were off and they showed no sings of life. Since then, my atom amp has turned back on but it outputs an
obnoxious sound like the one that came out of my speakers, even without any input at all, and my scarlet solo hasn't turned back on.
Have I killed my scarlet solo and atom amp? If so, was it something I did wrong with the wiring or can plugging a defective amp kill other components through rca?
Any help appreciated

santiagol
Unless I missed something, did you plug a preamp into an integrated amp input? That could be a no no.
@dill 
I just plugged my phone into the smsl with a aux/rca adapter and it works fine.
I think I fkd up then.
I don't understand why the rca outputs of the jds atom are incompatible with the amp though.
Also I used to have active speakers connected to the atom amp in the same configuration and it worked fine. 
What inputs are safe for the smsl amp?

If you didn't change the gain setting on the atom  the impedance mismatch from the smsl might have fried the atom and the scarlet if it was plugged into the atom. 
What you did was plug in rca outputs of the atom (now acting like a preamp) into the inputs of the SMSL SA-98E (this is an integrated amp which means a power amp & preamp in one unit). So, you are feeding one preamp into another (don't do that). It worked fine with the active speakers because the speakers have built in amps and the atom is acting like a preamp in that configuration, which it should.

" What inputs are safe for the smsl amp?" 
Line level inputs, cd player, DAC, tuner, phono amp, etc.

What you needed to use was a power amp only for your setup. That would be rca preamp input, speaker outputs, no volume control or headphone jack.
Unless your integrated can be reconfigured to be used as just a pre or just an amp with the use of jumpers or a bypass switch,it's not possible to plug in an outbourd pre.The inputs are only for source components.
@djones51 I think this is what happened, I certainly didn't unpress the gain button, and looking at the atom manual, it specifies the use of low gain when using it with speakers. 
So from what I understand my setup could work as long as I change the gain button on the atom every time I want to use the speakers? That seems pretty risky if I can fry 200$ worth of equipment at the press of a button or lack of thereof.
@dill : You can connect a preamp into another preamp. Just keep the volume control low so you don't overdrive preamp #2. 
So I had no idea that the smsl had a preamp and a power amp.
Audio can be very confusing, so thank you for clearing things up.
From what I understand, the impedance mismatch made the signal backfire into the amp and scarlet, frying them both.
I think I'm going to get a new atom amp and scarlet solo, since I need the microphone input, and I was happy with my atom amp. If I understood correctly, I would need a new power amp to make the speakers work.
Do you have any recommendations for a power amp around 100$? Otherwise, how do I ensure the new amp I'm getting doesn't also have a preamp?

@jtcf : See my above post.
You can connect a preamp into the aux input (or any high-level inputs) of an integrated amp. Just keep the volume control low so you don't overdrive the preamp section of the integrated amp.
@roberjerman I still think it's a bit risky. I could accidentally press the GAIN button on the atom amp and kill everything, so I would rather just get a new amp and be safe.
The SMSL SA 98E is a small class-D stereo power amp with a stereo volume control. 65wpc/8ohms, 80wpc/6ohms. The OP can use it with a pair of speakers. He does not need another power amp! Cost: $114. Made in Ch*na - where else! It does come with an external 32 volt power supply. Weight: 2.8 lbs.
The SMSL does NOT have a preamp stage. Just a passive volume pot and a pair of RCA jacks. So it is essentially a power amp! I recommend that you continue to use it with your speakers. Don't waste money on another power amp! If you get a new Atom (headphone amp?) use it just for phones.
@roberjerman Could I plug a scarlet solo into the SMSL? Or would I need to use a rca/aux adapter from my phone/pc?

Roberjerman:
You can connect a preamp into the aux input (or any high-level inputs) of an integrated amp. Just keep the volume control low so you don’t overdrive the preamp section of the integrated amp.
This is correct.

Santiagol:
From what I understand, the impedance mismatch made the signal backfire into the amp and scarlet, frying them both.
An impedance mismatch would only affect sonics, if it had any effect all. It would not cause damage.

Santiagol:
I could accidentally press the GAIN button on the atom amp and kill everything, so I would rather just get a new amp and be safe.
The high gain mode of the Atom provides a gain of around 12 db, which is perfectly reasonable for a preamp. Using that setting won’t hurt anything as long as the volume control is not cranked up too high. The recommendation in the manual to set the gain to low when using the RCA outputs is mainly intended to optimize the part of the volume control’s range that is used in typical setups, and perhaps also to optimize noise performance and sonics. And in some systems the low gain setting will not even be suitable when the RCA outputs are used, since that setting provides no gain.

Question: When you plugged or unplugged the cables connecting the Atom to the SMSL, did you have the components turned off? If not that is what might have caused the damage.

Regards,
-- Al

You can connect a line-level component into the SMSL safely by having the volume pot turned off.
Question: When you plugged or unplugged the cables connecting the Atom to the SMSL, did you have the components turned off? If not that is what might have caused the damage.
 The atom was turned on, and I think the smsl was also turned on. I also had the volume cranked pretty high on the atom, with GAIN turned on.
I'm still surprised that the atom and the scarlet died but the smsl is intact
@almarg 
Plugging and unplugging live components into each other can cause damaging transients! Don't do it! Turn everything off before plugging/unplugging cables!
@roberjerman 
I now think that I simply had the volume too high on the atom. I will definitely be more cautious next time!
I will also turn the components off before pluggin/unplugging!
What is a "Scarlet Solo"? A headphone amp? Does it have a volume control and a pair of RCA output jacks? If so, yes you can plug it into the SMSL. 
The atom was turned on, and I think the smsl was also turned on. I also had the volume cranked pretty high on the atom, with GAIN turned on.
Yes, that’s probably what caused the damage. Although it is sometimes ok to plug and unplug XLR cables with power on, ALWAYS turn power off before plugging or unplugging RCA cables.

Good luck. Regards,
-- Al

Santiagol, I'm so sorry this happened to you. I can imagine myself doing the same thing. There has been some great feedback here because of your post which will hopefully help the rest of us whom would make the same mistake in the future to avoid the same problem. Thanks for a great discussion.