Qusetion: dumping a cassette tape

There is a slight difference in speed compared to a data recorder but it shouldn't be a problem.
Volume should be adequate, definitely not too high, but louder helps because otherwise tape noise could potentially distort the signal.

I have used a Philips AQ6355 to dump some tapes. While it can be used as a data recorder it is a "normal" one.

Where did you come up with this idea? Sure there can be speed differences between recorders, but I don't think they are anyway intentional.

missumj: WAV2CAS should be fine... BTW openMSX can use WAV-files without conversion.

As far as I know the idea while defining standard was to use standard speed cassette recorder with standard sound output to avoid need for a special device... I think this fact was mentioned also in some early marketing material but I'm not quite sure about that anymore.

I have also noticed that MSX is not too picky about the speed... I remember that friend of mine had cassette recorder hooked up to an variable voltage PSU... Adjusting the voltage had practically direct relation to cassette drive spinning speed, so he was able to load the games a bit faster Maybe you have also just hooked it up with wrong PSU.

It was some universal adapter so that's entirely possible.

is a wav file which be recorded by a normal tape player can be converted to .cmt image correctly by wav2cas?