Warning: long post incoming.
Ratings can be tricky. Sansui used VA (volt-amps) for rating consumption on most models prior to about 1973-74. As implied by the term, this is simply the product of multiplying volts x amps to arrive at a measure of power consumption.
In more modern terms, power is usually rated in watts, which is still essentially volts multiplied by amps. However, there is the concept of "power factor correction" to take into account, and this is where it gets complicated. This varies by type of load (resistive versus inductive) and other factors in the design of the equipment under discussion. Motor and A/C compressor loads are among the most difficult to start and run. Hence why most larger motors and compressors in large cental air condensing units for a home are run at 240V, which halves the ampacity requirement, is more efficient, reduces the need for excessively heavy gauge wiring and makes for easier load balancing in a dual bus arrangement.
Anyway, Sansui was generally accurate in their stated consumption ratings - whether in VA or W - as given on the rear panel ID tag affixed to most models, so use that as your guideline. For equipment not so marked (as with some tube and very early solid state models) one will need to run the unit through an amp meter to measure consumption at high output level (and under load) to get an accurate idea of what power is being drawn. But then most such models of the era lacking ID plates are under 50 WPC output at 8 ohms. So, the consumption is not going to be anything near the power requirements of a 150-300 WPC amp, even when accounting for lesser efficiency of early designs where being miserly on power usage was not a consideration as it is with so many electrical devices now.
In the US, modern residential electrical services are typically 200 amps at 240 volts (with the 240V comprised of two seperate 120V lines fed in tandem with a common neutral and earth ground). This renders a total potential power consumption of 48KW. In practice, this amount of power is almost never used for any sustained period of time as the distribution grid here is not capable of delivering that full power to every house concurrently at all times. Many older homes still have only 100 or 125 amp services. You figure with electric heat, electric cooking appliances (stove/range/cooktop) electric clothes dryer, air conditioning and a home full of Tv's computers, and all other manner of appliances and devices, you can quickly run up a very large amount of power use. But not, generally speaking, all at once.
Consider that I have an automatoc 13kW backup generator at home. In the event of utility lower loss, I can run my home virtually unchanged from normal use (central heat, water heater, clothes dryer and oven are all natural gas which reduces electrical load considerably). I don't live in a large home, really fairly modest, so my power needs may not be typical but at 13kW max output (which is 52 amps per each of two 120V outputs) from the genset I can remain comfortable and use anything in the house as I would normally. The central air is the only load that will cause the generator to bog down momentarily - and then only on startup - such that the governor has to comlensate the engine speed up to meet the sudden increase in load demand on the gen head.
I post all of that to demonstrate that I think the transient peak consumption issue is being overstated to some extent. If these monster amps (B-2301 for example) are pulling 3X their rated consumption even if only for fractions of a second at a time, while under maximum output, I can't believe the amp would not suffer a catastrophic breakdown in short order. Sansui built them extraordinarily well, but I doubt a margin of triple the rated consumption is something thesd units will stand up to repeatedly.
Now, if you are running an amp hard and the house lights dim noticeably at peaks in the audio, then you have an issue that needs to be addressed for safety, if nothing else. Modern circuit breakers will trip on being overheated, and that is a good way to damage a breaker as they will get weak from being repeatedly tripped in such fashion. Substandard wiring can also be a fire hazard under the same circumstances.
Finally, when using step up or step down transformers, there is always some loss as nothing is 100% efficient. The loss is released as heat, which is why a step up/down will get noticeably warm, if not hot, to the touch. That loss needs to be factored in as well if you are using a step up/down that is barely adequate for the attached load.
albeit briefly, which could mean that plenty of step-down headroom is highly desirable. 