Per 
[Author's Note: This SCP is in need of a huge rewrite. I'm not proud of how it's laid out now, especially in comparison to my modern writing style.]
SCP-XXXX-1 (left) and SCP-XXXX-2 (right) at the recovery site.
Special Containment Procedures: SCP-XXXX is contained at the E Wing of Site-64. SCP-XXXX-1 must be stored in a padlock safe. SCP-XXXX-2 must sit on top of said safe, facing away from the wall as to prevent damage to it upon sudden activation. (See Addendum XXXX-3) Three guards are to be stationed outside of SCP-XXXX's containment chamber for the purpose of capturing any entities which enter the containment cell via SCP-XXXX. Entrance to the chamber is limited only to Personnel Level 3 and up for testing purposes only.
Description: SCP-XXXX is the collective term used to refer to two (2) Blackweb branded speakers. SCP-XXXX-1 has two knobs labelled "Volume" and "Bass," an indicator light, alongside two outlets labelled with an icon representing headphones and "Aux In" under the main speaker itself, similar to the typical speakers of this brand. SCP-XXXX-1 and SCP-XXXX-2 are connected via wire extending two meters.
When SCP-XXXX is plugged into power outlets, the indicator light at the bottom of SCP-XXXX-1 will light up, idling at a solid yellow color. When the knob labelled "Volume" is turned to increase volume, the light will begin to change from a yellow to a red the farther it's turned, eventually coming to a stop when the color of the light is solid red. Similarly, decreasing volume will cause the light to fade into a green color, stopping at solid green. The knob labeled "Bass" seems to have no affect on the indicator light.
Once activated, SCP-XXXX-1 will begin to hum, shortly before creating a sound wave similar to that of a sonic boom, creating a portal. The portal leads to a destination decided by the position of the Volume and Bass knobs on the face of SCP-XXXX-1. Numerous tests have concluded that the Volume knob affects the time period, while the Bass knob affects how distant from the current reality it'll take the user. (See Addendum XXXX-TBA)
SCP-XXXX-2 is barren of any features aside from the speaker itself, and seems to merely act as the destination, creating an output portal once an SCP-XXXX-1 instance from a different reality or time period has activated.
SCP-XXXX-A through SCP-XXXX-█ are anomalous entities retrieved via SCP-XXXX-2. These entities range from entirely human to completely extraterrestrial in nature.
When headphones of any kind are plugged into the appropriately labelled outlet, the wearer will begin hearing various sounds and, on some occasions, music. Subjects listening to the sounds have reported thunder, humming, and songs that appear to be completely original, with subjects claiming it "never plays the same song twice." The formatting and soundfont of said songs also changes every time, with subjects hearing synths and even full orchestras. Attempts to record these sounds for scanning purposes have been met with failure, as it appears the emitted sounds are sent directly to the wearer's auditory nerve, and is not actually emitted using soundwaves. The cause of these sounds is currently unknown.
On rare occasions, a voice can be heard narrating over the sounds or music. The voice has been reported to be different every time it's heard. The differences in question are known to be accent, language, and in some cases, even gender. Investigation is ongoing to determine if the voice is sapient.
Now classified as SCP-XXXX-3.
Due to the nature of SCP-XXXX-3, the object has been given its own classifications, and requires Level 4 Clearance to access.
For brevity, Addendum XXXX-1 has been cut from the document as it was, largely, uneventful.
Addendum XXXX-2
The following is the second conducted test of SCP-XXXX shortly after recovery on ██/4/2019.
EXPERIMENT LOG 2
DATE: ██/4/2019
TIME: 11:43 AM
SUBJECTS INVOLVED: D-7142 (Male, 27) and Dr. Naylar.
TEST INFO: D-5728 has been supplied with an earpiece in constant contact with Dr. Naylar at control. Test is being observed through an on-site camera.
[BEGIN LOG]
[D-5728 is told by Dr. Naylar to set SCP-XXXX-1's volume knob to 55%, and the Bass knob to 0%. D-5728 follows these instructions accordingly, and turns on SCP-XXXX-1. The object begins to shake a bit before creating its usual sound wave, causing a portal to appear in front of it. D-5728 staggers.]
D-5728: Agh! Shit, that was loud! Is that normal??
Dr. Naylar: Yes. What do you see through the portal?
[D-5728 starts inspecting the portal itself closely.]
D-5728: Shit, dude. I- I'm seeing the exact same room I'm currently in, just from a different angle, I think?
Dr. Naylar: Please enter the portal.
[Hesitantly, D-5728 nods before stepping inside the portal. Dr. Naylar at control tries speaking to D-5728 with no avail. The portal suddenly closed and vanished, taking D-5728 with it. A Site-wide search was commenced, but D-5728 was nowhere to be found, and deemed missing.]
[END LOG]
[LOG REOPENED]
Approximately one week after the proceeding test occurred, SCP-XXXX-2 created a portal in the likeness of the same portal produced by SCP-XXXX-1 one week prior, the likes of which was exited by D-5728. Subject was immediately re-contained and interrogated. When asked about his location during the 1 week since his absense, D-5728 was confused and stated he started performing the test only minutes ago. D-5728 has since been terminated.
[END LOG]
Closing Statement: None.
Addendum XXXX-3
Date of Occurance: ██/6/2019
After approximately two months of inactivity, video surveillance picked up a portal opened by SCP-XXXX-2. A human male, later confirmed to be named Daniel, and now classified as SCP-XXXX-A, got thrown through the portal and landed on the floor of SCP-XXXX's containment room. The portal closed as SCP-XXXX-A panicked and tried escaping the room to no avail. Subject was eventually apprehended by on-site guards. Tests confirmed SCP-XXXX-A is, by all accounts, an average male of American dissent in his early 20s, with the only noted anomalous property being an immunity to amenstics. The source of this immunity has not yet been found. SCP-XXXX-A is currently contained in a D-Class cell in the D Wing of Site-64.
Addendum XXXX-4
Interview Log 1
Date: ██/6/2019
Interviewed: SCP-XXXX-A
Interviewer: Dr. Naylar
Foreword: Dr. Naylar entered the interview room not long after SCP-XXXX-A woke up.
SCP-XXXX-A: Wh-Who are you?! Where am I!? What the hell is going on?
Dr. Naylar: Hey, hey, take it easy. We just want to talk.
[Dr. Naylar sits down in a chair on the opposite end of the table.]
SCP-XXXX-A: Wha-… Please, tell me where I am…
Dr. Naylar: That's classified. Please calm down, we have no intentions of harming you. What is your name?
SCP-XXXX-A: … D-… Daniel.
Dr. Naylar: Nice to meet you, Daniel. My name is Dr. Naylar. We just have a few questions to ask you, if you'll be willing to answer them.
[SCP-XXXX-A remains silent and slowly nods.]
Dr. Naylar: Very good. Now, do you remember what happened to you?
SCP-XXXX-A: Wh- What do you mean?
Dr. Naylar: A set of speakers, a portal… Do any of those ring bells?
SCP-XXXX-A: O-Oh, that's right… The freaking… I… [Daniel takes a deep breath and calms down.] I had just gotten my hands on a new computer. It was expensive as hell. I remember plugging it in. Everything seemed to work just fine. It was a gaming PC, I got an HD monitor, and I was ready to play the fuck out of some video games. Of course, it was only then I realized I didn't have headphones or speakers of any kind… Well, I thought, anyway..
Dr. Naylar: You thought?
SCP-XXXX-A: I don't remember putting them there, let alone having them in the first place, but after I finished my PC and turned around, those speakers were just sitting there, on my bed. It was freaky shit… They had a note on them.
Dr. Naylar: A note?
SCP-XXXX-A: Yeah. I think it read… "Consider this a gift from me to you." It was unsigned.
Dr. Naylar: And no one you knew posted this note?
SCP-XXXX-A: The only one I can think who would do this is my friend Dave. He's prankster, but… I'm not stupid. This is no prank.
Dr. Naylar: We're getting side-tracked. What happened after you found the speakers?
SCP-XXXX-A: I plugged them into my new PC, and into an outlet. I tried to turn them on… Everything after that is a blurry mess I can't make out. I think I saw.. someone else?
Dr. Naylar: Someone else? What did they look like?
[SCP-XXXX-A scratches its head.]
SCP-XXXX-A: Heck… Sorry, doc, I can't remember. It all happened so fast, I couldn't make it out… Next thing I know, I ended up… here…
Dr. Naylar: I see. Thank you for your report, Daniel. I think we can-
SCP-XXXX-A: H-Holy shit…
Dr. Naylar: Hm? Daniel?
[SCP-XXXX-A is silent for several seconds.]
SCP-XXXX-A: I… I know that icon. That symbol.
Dr. Naylar: W-.. What?
SCP-XXXX-A: Y-Yeah, that's the… The SCP Foundation..
Dr. Naylar: The- what..? How do you know that?
SCP-XXXX-A: I'm… I'm in SCP Foundation custody, aren't I?
Dr. Naylar: Daniel, I need you to elaborate. How do you know all this?
SCP-XXXX-A: Shit, ok, let's see… Where I'm from, at least, the SCP Foundation is fake.
Dr. Naylar: And how do you know that?
[SCP-XXXX-A noticably becomes much more calm and collected.]
SCP-XXXX-A: Everyone does. In my… reality, I suppose, the Foundation is a fictional website. scp-wiki.net. Using this website, People of any and all sorts create the objects you have in Foundation custody… And then some.
Dr. Naylar: scp-wiki.net? So we're all just fiction?
SCP-XXXX-A: Obviously not, seeing as I'm being interviewed by a Foundation member and everything.
Dr. Naylar: You're taking this whole thing rather well.
SCP-XXXX-A: It's a coping mechanism, and to be honest, it ain't working. Excuse me for a second while I freak out.
[SCP-XXXX-A then proceeded to start yelling and screaming before being forcibly removed from the interview room, and brought to containment.]
[END LOG]
Closing Statement: "I don't know what's more intriguing. The fact that SCP-XXXX brought us an individual from an alternate reality, or the fact that the Foundation is mere fiction in said reality. I'm incredibly curious to learn more about the Foundation of Daniel's reality, and its significance to our reality. Daniel is at risk of revealing confidential info to personnel who aren't authorized. We attempted applying Class █ amnestics to Daniel, but those proved ineffective. My guess is that beings from alternate realities are immune to such effects, but don't take that info to heart. It is merely a theory on my end. Regardless, thanks to this, we're reclassifying Daniel as SCP-XXXX-A. Further objects or subjects recovered from SCP-XXXX-2 will be given similar classifications if they also prove to be anomalous somehow." -Dr. Naylar
[Author's note: Move Dr. Naylar's "I don't know what's more intriguing" lines to future interviews with Daniel. This first one should put attention on how Daniel is immune to amnestics.]
Proceeding Interview Log 1, further interviews with SCP-XXXX-A now requires O5 approval and supervision, as SCP-XXXX-A could leak confidential info to unauthorized staff.
Addendum XXXX-5
TBA testing log for headphone jack yadda yadda