In case anybody has the same question: yes, the Audigy RX works very well with larger Soundfonts (like the Arachno Soundfont) on Win 7 64 Bit and more than 4 GB of memory (I have 16 GB at the moment). I have no distortions any more and even EAX works very well. I've tested Doom 3, Titan Quest and Quake 4. All games worked very well.

But I have to say the Card lacks quite a bit of sound quality. Coming from a Asus Essence STX II I miss the clearance of the Mids and the very low End Bass. The RX also has trouble with large Signals. As soon as there are really loud and deep Explosions, the Audigy RX gets a bit distortions. I don't know if it is noticable on cheap Headphones. But it is clearly audible on my combo (Soundcard -> Violectric V90 Headamp -> AKG 701 and/or Fostex TH 600 Headphones).

But since this card gives me so much joy with Soundfonts and EAX, I will keep it. Its a good bargain for ~50 Euros.

Oh! Do yourself a favor and don't activate "Bit-Matched Playback" at the Audigy Console. It will bring you heavy sound stuttering and distorsions on Doom 3 and Quake 4. I played with it and forget about it. Had some hassle to find out which feature gave me the distortions.

I have an Audigy 2 and I have to reduce the sound card volume to about 75-80% otherwise there is clipping of the signal. Have you tried reducing the master volume?

Hello Stretch, yes, I also use the reduced master volume as a workaround. I am able to reach painfull volume levels even at 75% master volume with the violectric headamp, but it's a bit odd that a soundcard needs to have such a workaround in 2016. Remember: I got used to a STX II for about a year 😉

Another workaround that works at least with Danel K drivers: you can set the bass boost level at around 40 to 45 Hz and give 10% bass boost. This will help the lack of deep bass.

As there are more than 100 clicks, I want to keep you updated. I've mentioned the heard lack of sound quality. And I couldn't get used to it. So I got myself a X-Fi Titanium HD. What can I say? That card is the right mixture of the the Audigy and the Asus STX II. It plays MIDI Files on the Hardware Synth and Sounds amazing. CMSS3D is WAY clearer and really usefull at the Titanium HD. CMSS3D / CMSS3D 2 at the Audigy RX is quite muddy and indifferent. Its better to turn it off on the RX since it doesn't give you a advantage in 3D Games.

The only drawback is, that there is sometimes a distortion (hissing, crackling, screech noises, sometimes missing notes) when I play MIDI Files at the Titanium HD. But not always. I can't identify the cases where it works and where it doesn't. Interesting enough, I have never had a single hiss, scratch or stutter on the Audigy RX. But it sounds really muddy.

All in all the Audigy RX is a good card, but it would have been good if creative had improved the sound quality - at least the channel separation and the signal to noise ratio.

//Update: the Titanium HD works now flawless. The original Drivers that came with the card did the trick. Don't ask me why. But I'm really happy now and will sell my STX II