I suspect that the clipping indicator may be coming on when levels hit 0 dBFS, or even a hair below... >0dBFS detection requires oversampling and the additional system load would not generally be considered acceptable, although it's not an uncommon feature in DAWs these days. Try generating a few sines in Audacity (amplitude = 0.99995, 0.999, 0.985, 0.95, 0.9, 0.8 etc.) and playing those in one of the players, and see what the threshold is.
The problem should basically solve itself by the time you start using ReplayGain in Foobar, which I very much recommend you do. (RG settings are in Preferences: Playback. I even have my RG preamplification set to -3.2 dB with / - 9.2 dB without RG info, a few '80s releases from my collection actually are that dynamic. If you never ever see any positive album gain, you probably won't need to go this low, you may even be able to afford +2 or 3 dB.)
Assuming basic tagging, RG scanning your entire collection in Foobar should be as simple as dropping all of it into a new playlist (an opportunity to sort out any untagged "bad apples"), marking all e.g. via Ctrl-A, right-clicking and selecting "ReplayGain" --> "Scan as albums (by tags)" from the context menu.