Fast Recorder

Windows puts quite the variety of utilities at your disposal by default to help with a bit of everything. It also includes a sound recorder you can use to capture speaker sound with the right configuration. Alternatives are also available over the web, and Fast Recorder is a suitable example to quickly generate audio files.

Perks of portability

A cool thing about it is portability. This saves you some time and effort of going through a setup process, thus making it possible to store it on a USB flash drive along with other tools you might need for audio processing. Runtime has little to no impact on the health status of the target PC, and this is mostly because registry entries remain unaffected.
The application doesn't start recording directly on launch, even though its name states that it's fast. It is, but you need to interact with the corresponding tray icon to start the session. A slim window shows up on the desktop, with a timer letting you know the session started. There's also a volume indicator, as well as buttons to cancel, or end the recording.

Files automatically saved to a custom location

Stopping the process saves the audio file, while hitting cancel drop every capture bit of sound. By default, the application records from a connected or built-in microphone, but you can also capture speaker sound by switching the system recording device to stereo mix. Even when stopped, the application still remains in the tray area to be ready for a new session.
It's a good idea to pay a visit to the options panel first, otherwise you end up scratching your head and not knowing where files are saved. There's no prompt for the generated file, and the audio recording is always exported to the specific location. A name tag can also be added, with the program adding numbers in case of name conflicts to prevent overwriting previous recordings.

To end with

All things considered, we come to the conclusion that Fast Recorder is indeed a fast method of capturing sound from microphone or speakers. It starts when you interact with it, saving files under custom names and locations. It could have used other export formats besides WAV, but it's sure to get the job properly done.