Product From USA 
The Original American Stereophone Company
In 1958 John C. Koss changed the way we all listen to music when he invented the world's first SP/3 stereophone.
Koss sought to replicate the excitement of a live musical performance, allowing listeners to experience sound as they had never before, bringing them closer to the music they love. Music lovers around the world recognize that dedication to accuracy in sound reproduction as: The Sound of Koss
Before the world's first SP/3 Stereophone in 1958, John C. Koss developed a portable stereo photograph player with side-wing speakers.
in 1958 John C. Koss invented the world's first SP/3 Stereophone introducing personal stereo audio to the world.
In 1960 Koss released the predecessor to the SP/3 with a lighter design, more comfortable headband and superior sound quality.
In 1970 Pro/4AA set the standard for full-size professional headphones delivering true full frequency performance.
On June 25, 1971 John C. Koss unveiled the new Koss World Headquarters in Milwaukee, Wisconsin.
In 1974, Koss released the HV/1A the first dynamic headphone capable of reproducing all 10 audible octaves.
In 1984 the acclaimed Porta Pro was released and set performance and comfort standards worldwide for decades to come.
In 1989 the JCK/300 Kordless Headphone system set the standard for infrared wireless headphones.
In 1990 Koss's revolutionary ESP/950 electrostatic headphones introduced breakthrough high-fidelity sound.
Carrying on the legacy of the Pro/4 line, 2014's Pro4S Studio Headphone was specifically designed for audio professionals.
In 2017 Koss released the acclaimed KPH30i featuring an ultra-light weight design with remarkable high-fidelity sound.
In 2021 Koss Utility Series introduced three new headphones allowing listeners to connect via Lightning, USB-C and 3.5mm.
In 2023 Koss continued it's evolution of wireless headphones with the TWS250i True Wireless Earbuds.
 |  |  |  |  | |
|---|---|---|---|---|---|
| Koss X Retrospekt P21 Retro Headphone | Koss Porta Pro | Koss KPH30i RB | Koss KTXPro1 | Koss Pro4S | |
| Customer Reviews | 45 | 15,832 | 3,314 | 3,373 | 347 |
| Price | $32.00 | $39.99 | $29.99 | $19.99 | $99.99 |
| Type | Headphones | headphones | Headphones | Headphones | Headphones |
| Fit | On-Ear | On-Ear | On-Ear | On-Ear | Over-Ear |
| Sound | Balanced for personal listening | Classic Porta Pro sound with exceptionally deep bass | Balanced for personal listening | Balanced for personal listening | Balanced for personal listening |
| Comfort | Adjustable headband for the perfect fit | Comfort Zone temporal pads & custom fitting earcups | Sling headband & patent pending earcup suspension | Sling headband & patent pending earcup suspension | Lightweight, for all day comfort |
| Cushion | Soft foam (replaceable) | Soft foam (replaceable) | Soft foam (replaceable) | Soft foam (replaceable) | Soft Leatherette |
| Age Range (Description) | Adult |
|---|---|
| Material | Stainless Steel, Metal |
| Headphones Jack | 3.5 mm Jack |
| Ear Placement | On Ear |
| Impedance | 32 Ohm |
| Sensitivity | 104 dB |
| Control Type | Media Control |
| Cable Feature | Retractable |
| Number of Items | 1 |
| Has Self Adjusting Headband | Yes |
| Replacement Ear Pads | No |
| Has Adjustable Earcups | Yes |
| Has Adjustable Headband | Yes |
| Package Dimensions | 8.31 x 6.06 x 2.13 inches |
|---|---|
| Item Weight | 3.84 ounces |
| ASIN | B092DX27G9 |
| Item model number | P21 |
| Customer Reviews | 4.1 4.1 out of 5 stars 45 ratings 4.1 out of 5 stars |
| Best Sellers Rank | #30,105 in Electronics (See Top 100 in Electronics) #599 in On-Ear Headphones |
| Date First Available | April 13, 2021 |
| Manufacturer | Koss Corporation |
| Brand | Koss |
| Color | Orange |
| Form Factor | On Ear |
| Connectivity Technology | Wired |
| Special Feature | Adjustable headband |
