I now did the DPCLAT test, after downloading the appropriate software. There was 1 abnormality, which went away after I got rid of the Alesis Vortex item from my Device Manager. However, that didn't stop the popping.
LNovik

Have you tried adjusting the midi playback buffers ?
. . . though it seems you're only getting the popping / crackling when recording through the soundcard.
Make sure there is no clipping in the Delta Control Panel, and that the gain staging in Sonar is not clipping anywhere when recording midi to audio.
With my Delta 66 (driver version 6.0.8 for WinPro SP1 64 bit), I use ASIO . . . but as stated, find which works best for your hardware.
If you post your system specs in your forum signature it helps give a clearer picture of your set-up.
 
Also, I might add, that I have in the past had this popping / crackling sound, especially when I upgraded to the Sonar X series . . . but by adjusting settings in Sonar Preferences and the Delta Control Panel, I eventually found the right settings that worked for my Delta 66.

OK, I'll try to answer all the questions. Noynekker: other people have suggested that I post my system specs, so I'll start the preliminaries to that process now. The problem is: I don't know what half the things represent in your list (the 2nd half,) so I'm not sure if I'll be including everything there is to note.
Perhaps you can tell me what you think is missing. I'll then try to post it in my system specs.
Sonar Producer 8.5, M-Audio Delta 66, Midisport 4x4, Intel i5 650 @ 3.2 gHz, 6.0GB RAM, 64 Bit OS.
I guess I could find other specs, such as the graphics card, etc, if you think that would be helpful.
 
As for my problem, I have now downloaded what looks to be the latest Windows M-Audio driver from the M-Audio Forum, and that did not make any difference.
 
I was able to make sure there was no clipping when I recorded. On Sonar, as I have said, when I was watching the MIDI track record to the audio track, there was no clipping, and I'd say it only went up about 7/8 of the way to the top (I know I"m not using the correct terms.) When I viewed the same process on my M-Audio Control Panel, I don't even think the input sound bars were going up 1/2 way up to the top. In any rate, there was no clipping--assuming clipping means the input was too hot and the meters were at max.
 
I've tried multiple instances of buffers, etc. For instance, now, in my M-Audio control panel, the buffer size is on 512. In Sonar, under options\Audio, I now have buffers in playback queue at 8, and buffer size at 23 msec (though I've tried many other variations as well.) On the next (Advanced) page, I have Playback buffer size output at 512. OF course, there are all these other fields, such as "enable read caching and enable write caching, which are both checked. There is also a Record buffer size output, which is at 256 and not editable. 
Lastly, I should add that as I was fiddling around, I just changed my M-Audio driver setting from Delta 66 1/2 to Delta 66 multi 1/2. When I  recorded with these parameters, 2 interesting things occurred. First, I was not able to get a very hot signal, similar to my problem when I was using the ASIO driver. It would only go up about 2/3 of the way toward the "hot" zone. However, I did NOT get any popping. WHen I re-recorded and cranked up the volume even more, though not enough to get even close to clipping, I then again heard the crackling.
 
I'm hoping that the more details I share, the more someone might be able to  figure this out. I'm of course, open to trying more setting variations. Perhaps, since Nohynekker has a similar soundcard, he could make some suggestions.
 
Looking back, about the only thing I haven't checked is "IRQ's. Unfortunately, though I have heard the term, I'm
not familiar with it. I don't see any tests for it.
 
 
Thanks again to everyone for their interest.
 
LNovik
 

Does it pop when using headphones only?
Eight buffers in playback queue seems high.

Well, I didn't start with 8 buffers, but someone told me to increase my buffers--or, at least, that was my understanding. Originally, it was at 2 buffers. ANd yes, I DO hear the popping when using headphones. I haven't tried it any other way, as I am used to playing like this most of the time. I guess I could try to see if it does not occur when using my speakers, though, again, I didn't used to have this problem when using headphones. I will try it without the headphones, and then, with other headphones.
I guess I'll turn down the buffers to ?4. This is what I'm looking for: specific numbers for specific parameters.
Thanks.
LNovik

And yes, it DOES occur even with my speakers. Again, I'm wondering if the signal is too hot, and thus causes the crackling. However, as I've said, the meters don't suggest that. In addition, the end audio result is just mildly louder than the MIDI version that I heard when recording it. That seems to be what I've seen before.
LNovik

I was just reading a post on Gear slutz and apparently there is no W7 64 drivers for the Delta 66, correct me if wrong. But it seems that card is really hard to work with on a modern system.

Cactus Music
I was just reading a post on Gear slutz and apparently there is no W7 64 drivers for the Delta 66, correct me if wrong. But it seems that card is really hard to work with on a modern system.

There are drivers for Windows 7 64-bit SP1.

Yes, those were the drivers I downloaded this AM.
I am also thinking that I may just have to get a new soundcard. I have seen many. I would think that I just need an updated version of the type of PCI type card I have now. I'm not sure I need that type, but I just don't need things like mike inputs, since they go into my mixer. I also don't care what company, as long as the reviews are favorable.
I would want a good one, but this is my hobby, not my job. Any suggestions?
I'm also not closed to hearing any more suggestions about how to fix my system with the card I have.
Thanks again.
LNovik

hmmm . . . think I might be running out of helpful suggestions here.
So you're on Win 7 64 bit . . . but did you install Sonar 8.5  - 64 bit or 32 bit version ?
It's been a while, but I recall when I was running Delta 66 with Sonar 8.5 (32 bit version), I was using the WDM drivers. There was also something called "Wave Profiler" in the preferences, that you could run, that helped optimize the driver for Sonar.
I have "buffers in playback queue" set to 2.
Are you using Sample Rate 44.1 KHz ?
Are you using an Audio Driver bit depth of 16 or 24 ?
 
I don't think it would be that helpful to let you know which exact Sonar preferences settings I use because our computer hardware and software situations are so different . . . but as far as the Delta Control Panel settings:
- - Mixer tab . . . everything is routed to Master (1/2 in + 3/4 in - - -  are all muted)
- - on the Input tab . . . have you tried the different settings for +4bd, Consumer, and -10db ?
- - on the Output tab . . . 1/2 out have the output source set to "mixer"
Again, these settings are designed to work with my external Tascam mixer.
 
I really hope you can get your Delta 66 working on your existing system. It's worked for my purposes for a very long time through 3 computers Win 98, Win XP, and Win 7