Hello - I've used DCC and Sound for a number of years now. It certainly seems that OEM / manufacturers have a hard time maintaining a high quality product line, be it Athearn, BW, or any of them.
Recently I purchased two brand new Athearn Genesis SD45-2 engines (identical except road numbers) with Soundtraxx Tsunamis installed. One of them ran just fine out of the box, GOOD sound, good motive power, smooth, etc. The other one had multiple problems: Decoder overheating (even with sound disabled) after a few laps around layout (not a huge layout); Sound levels simply not adjustable by any technique known to me or in any manuals (I used Digitrax 402's and standard base stations). The 'good' loco's sound can be adjusted from very low (or off?) to near room-filling levels. The bad one simply would not change its sound level, up or down, no matter what entries were made in relevant CV's, including 128,128,130 - 134 - all the main volume settings.
I have ALL the relevant manuals and am well experienced using sound decoders from Digitrax and Soundtraxx.
I sent this 'bad' loco back to the hobby shop (about 6 hrs drive away), and the gentleman there sent it back to Athearn/Horizon. In a very few days, a second one arrived here, from Athearn via the hobby shop. Frustratingly, it too has only a very low to moderate sound volume, not adjustable up at all, but down to inaudible. I copied ALL the relevant settings from the 'good' loco to this one, and the sound is still mediocre to low. I hate to send it back again, the shop owner is a good friend and an honest gentleman, and frankly it's a lot of bother.
I have to report that, over the years, my experience with various companies' model locos with 'factory' sound is less than satisfactory - somewhere well below 50% acceptable. This includes samples from nearly all major providers. The only *consistently* acceptable (very good, really) factory-sound equipped locos I have are all Proto 2k from Walthers, especially the GN Empire Builder F7's (all four of them, A-B-B-A).
On the other hand, I've done quite well with self-installed decoders, including Soundtraxx's earlier sound-only devices, in older Athearn blue-box locos. Others have, too, but they are getting hard to find. At a recent moderately large train show I could only find one or two blue-box loco offerings that appeared to be 'new in box'.
I am definitely going to correspond with the manufacturer and (again) with Soundtraxx, who has always been helpful in the past. I also would like to hear others' experience along this line, if any. I know loco-to-loco variations should be expected, but not max sound levels *widely* different.
jrc