Most in ear headphones or earphones are typically highly efficient so they work well with smartphones or other portable devices without requiring an amp. You do not need a headphone amp when using noise-cancelling headphones, as they essentially already have a built-in headphone amp inside.

Most headphone amplifiers provide power between 10 mW and 2 W depending on the specific headphone being used and the design of the amplifier.

Aside from the output of a mic preamp, other examples of line level signals are the headphone output of your phone, the aux input on your car stereo, or the output of an audio mixer.

there is ZERO chance of using a headphone OUTPUT as an INPUT. generally all inputs can not be used as outputs and all outputs can not be used as inputs. the only exceptions are hdmi (arc) and on some soundcards which are wired to allow for port swapping.

There is no difference but the name. Both would be designed to be used with a source that puts out about 2v max. If an input is labeled “phono” it may have a phone preamp connected for turntables that do not have one built in or it may be a line level audio input labeled for use with a turntable with a preamp built in.

An auxiliary port (AUX) is a type of standard communications port on a device that accommodates audio signals for: MP3 players. Headphones and headsets. And other audio devices, including some fairly traditional audio technologies.

Interfaces and their connectors

This article details information regarding common audio connections.

• Optical (Toslink)
• Coaxial (SPDIF Coax)
• HDMI (High Definition Multimedia Interface)
• RF Coax.
• A/V Jacks.
• Analog Audio (RCA) – Two Speakers.
• Digital (Compressed) – Five Speakers.

Yes, you can USUALLY run 25 or 50 feet of regular line level RCA-type cable in a typical house without worrying about hum induced in the cable.

Cable length does affect sound quality – the shorter the cable, the better the sound quality. Sound quality is also affected by the thickness of the cable and the wire’s material. Thicker cables tend to produce better audio signals.

With speaker cables I like to stay under ten feet, and find eight feet to be the most popular and practical length. In a system where components are grouped closely together, one meter cables are the norm, but if the amplifiers are sited further away three to five meters isn’t uncommon.

The thicker a wire or the lower the gauge, the less resistance. It is therefore a combination between speaker impedance, length and gauge that affects the resistance.

The shorter the wire is, the less resistance it will have. The thicker a wire or the lower the gauge, the less resistance. It is therefore a combination between speaker impedance, length and gauge that affects the resistance.

Most systems will use 16, 14 or 12-gauge AWS wire. 16-gauge copper wire can run up to 48-feet with 8-ohm speakers. So, if you want a wire size that will suit most circumstances, then a 16-gauge copper wire is probably a good fit. For speakers with a lower impedance, then you might go with 12 or 14 AWG just to be safe.

If you have a modest system, investing in expensive cables may not be the best way to spend your money. Cables make a difference, but it’s a smaller difference than upgrading speakers, electronics, or turntable systems. The Cable Company also has a headphone lending library, for headphones that sell for more than $600.