So besides spreading the news...what are people's opinions?
If a Variac is necessary in you opinion what do your recommend....nothing expense.
BIT OF A RANT WARNING!
I will assume that you have verified the line voltage coming into your dwelling as being within tariff, and within the safe operating parameters of your equipment. Generally that is somewhere between 110 and 120 VAC. Note that typical tariffs call off some percentage above/below some fixed voltage, these days usually 120 VAC.
With that in mind, a Variac is a dangerously useless addition to your system, especially if operated anywhere near its capacity. Keep in mind that these devices were originally designed to dim incandescent light loads in theater applications, not as a buck/boost device. How they inveigled themselves into this application is a mystery to me. Perhaps as a (very) temporary expedient to determine the range of a problem and how much correction - temporary or permanent - is needed. But, certainly, no more.
If you do have a permanent/ongoing or constant high/low voltage problem, or unacceptable voltage sags for extended periods, then a solution outside of a Variac is necessary. There are specific devices for the purpose that do an adequate job and are one helluvalot safer than a Variac.
Is one such device from one such source. 2,400 watts (20A) should be enough for about any audio system, even one that is tube-based. But there are many such devices from any number of sources. BUT - In terms of capacity, allow for at least 2 X the anticipated load for the stabilizer/conditioner.
Variacs have no place in the electronics hobby whatsoever unless they are metered for both voltage and output. Otherwise, not at all, ever, full stop.
I keep a Heathkit IP5220 which also serves as an isolation transformer - and an immensely useful diagnostic device. Similar devices are made by VIZ, RCA, TEMA, B&K and many others.
Best of luck with it - but lose the Variac as a buck/boost device!