Poweramp uses 512x152 and 1024x1024 (HD) textures, and downloads images up to 1024x1024 (normal) and 2048x2048 (hi-res). All the options are available in settings / Album Art, but if you have device with limited per-app memory settings, low-res screen, or older Androids (5/6), you better avoid enabling HD / 24bit album art as it will waste memory and push other images out of cache.