We have an 05 Prius with 175k.
Sounds like noisy valves but they are all well within spec. Timing chain, guides, tensioner all appear fine. Possibly intake vvt gear or solenoid?
Common problem?
something like this happened to a Guy at work, his had 199k on it when it happened. I guess the oil pan filter got shitty and started building up sludge and grim, it wasn’t letting enough oil into the motor so it was a noisy valve train.
he replaced it and ran some seafoam through it, no problems since
Is the noise constant? Generally a bad VVT gear will only be noisey on start up, not all the time.
Assuming its happening all the time, Im going to guess gunked oil pump pickup, and/or gunked up VVT solenoid. I believe there is a screen on either the solenoid itself or the banjo bolt where the oil line feeds into the head.
i miss this toyota tech at work ^^ 
Thanks for the responses guys.
Noise is constant, not audible at idle.
Screen for the solenoid is clean, oil pump pickup is clean.
Then I would check oil pressure maybe the pump is shitting the bed
Usually when the VVT-I sprocket goes bad it sets a code for being over retarded. Same with the solenoid going bad or getting gunked up. I’ve replaced lash adjusters on them for being out of tolerance causing noises at higher mileage but that’s rare. They will “feel” tight but we’re talking something you need a micrometer to check. My 1st instinct is something with the chain system but if you’re sure that looks good then it’s hard to help without looking at it. Keep us posted on what you check and find.