I am getting a DH165LO decoder and a SFX004 Soundbug.
Will these function on standard DC power?
The DH165 series has "analog mode conversion"; the default setting is for operation in both DC and DCC environments.
There are some that do not want this feature, and it can be disabled by setting CV29.
The SFX004 also operates in a DC environment, and the analog mode conversion can be turned off via CV29.
If so, how?
Early on, Digitrax recognized that locomotives are sometimes operated in DC environments, and the conversion feature was built into the firmware.
In practice, those operating in DCC-only environments have found that the conversion feature can sometimes result in unpredictable operation, so many disable this feature.
Although the decoders still have the analog mode conversion feature, this is typically no longer mentioned in the documentation.
It should also be noted that you will lose some features, or their performance will be restricted, when operating in the DC environment.