There are three ways for Windows to access an audio card: Via an MME (MultiMedia Extensions) driver This system has been around since Windows 3.0, and it is this type of driver that is normally installed in the Control Panel and via Plug'n'Play. Most regular sound playback (like when Windows goes "bing" on startup) happens via MME.
- Practically all cards come with an MME driver. If your card appears in the System part of the Control Panel, you have an MME driver installed.
- Using a card via an MME driver gives you the worst latency figures, especially under Windows 98.
- Only one program at a time can use a card accessed via MME.
Via a DirectX driver DirectX is a later system developed by Microsoft to provide developers with more efficient routines to access audio.
- Not all cards come with DirectX drivers. However, drivers for some cards are included with DirectX itself.
- Using a card via a DirectX driver gives you a shorter latency, between 40 and 90 milliseconds.
- If you use DirectX 3 or later, all programs that access the card via DirectX and make use of the DirectX "secondary buffer" feature can use it at the same time, and Reason Adapted version 4 can play in the background.
Note: Only use DirectX if you are sure that there is a "certified" DirectX driver installed for your sound card. If in doubt, contact your audio card vendor to check whether there's a DirectX driver for your card or not. More information about DirectX can be found on Microsoft's DirectX web pages.
Via an ASIO driver This is your best option if it is available. More and more audio cards designed for serious music and audio use come with ASIO drivers. As stated above, ASIO does not guarantee low latency, but it allows for it if the audio card designers take advantage of its possibilities.
- Not all cards come with ASIO drivers. If in doubt, check with the audio card manufacturer.
- Using a card via an ASIO driver can give latency figures as low as 3ms.
- When you use ASIO, only one program at a time can access the card.
More information about ASIO can be found on Steinberg Media Technologies' web pages.