need to break in equip after prolonged non-use?

If any amp or preamp has been sitting for a while, the filter capacitors in the power supplies will have to 'form up' again which can take some time. Until that time the equipment won't sound right.

If its been sitting too long the filter caps can fail. They are not unlike batteries in that regard, but usually it would take several years for that to occur.

I have always found that, yes, it will need to re-break-in, but nowhere near the length of time the first time around.

I asked Jorma Kosky from Jorma Design cables that same question. Specifically I asked him if I hadn't used my speaker cables in 6 months, how long would they require reach the same level of break in again? This was his response -

When the cables have not been used since then, they need a little time, I can not say how long, it depends on so many factors.

The same principle can be applied to components. You certainly don't go back to square one, but I would think your gear would need 1-2 weeks regularly playing a signal to be refreshed.

Aesthetix told me that my Romulus CD Player, that had not been plugged in for six months, would need about a month to be at full performance...