I have a slightly different take on this. Just get the following and put it in the simplest box you can find, if you do not care about how it looks. Besides you could always change the case later on. All the DIY that would be needed on this would be to hook-up the RCA to the pre, the pre to the amp board and the amp board to the binding posts. Even the simplest electronics technician would be able to help you with this...
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you are correct ..
but I do care about looks people likeme ( many newbies too) the cabinet issue starts .Hooking rca switch etc to a iron box or plastic can be a rough option .consider these i some cases iron cheap boxes will be rusty,paint will peeling,manually drilled cut aluminum boxes will make amp look like school project,getting good finish is really tough.
, many of the technicians will mishandle the kit (many cases i heard people have come to me for help )
options newcomers can choose are
A)Hasslefree Start :
click on S.M.S.L SA-36Aand but the amp, after arrival start listening ~2000Rs
or ,
Muse TA2020 : excellent value ,tested by FM
or
Topping TP20:excellent value ,tested by FM
A wow looking AMP for initial setup
After a while add a SSP(preamp,get the kit from the FM),some one test it.
B)little costly start but good :
*buy soldering/wire/flux n supplies
*buy list by gruby ,the list is good just add a 0-24V power supply, i have tested the whole set it is excellent buy..but yup investment goes to 10k or 12 k with express shipping.
*bend Aluminum/paint old cabbie/get cabiie from VCD player,fit wood
end product :good sounding amp just looks is 3 out of 10.
C)Lowcost but time and effort:
Buy Helder MKII kit ,procure others add a linear PSU with ei core trafo.
I did this!! in <5K you have a very good amp ready running.
a)make sure you keep a regulated PSU .keeping voltage approx 12V or run from some protection device like stabilizer.
12v regulator can be made with power mosfet+LM317 :like this
LM317 High Current Voltage Regulator - Electric Circuit
or ,
b)Buy 12V 3A SMPS from ebay india
It is individual choice