The EAR 834P is a good phono which can be better ! I never mod mine as I am talking like over 10 years ago when used one and when I did it was for a second system as my Convergent CAT SL1 was the main phono pre-amp. However I read that the Step up Transformers (SUT) used inside were cheap and not very good. The caps used as well were very average. Since then I have read a number of people copying the circuit and having great results. I recently visited someone who upgraded the SUT and had fantastic results. So in general the MM circuit is very good. At the time I changed my tubes to ribbed Telefunken (I did not pay USD 2000 for my tubes, which sounds excessive - a matched pair gold feet ribbed ECC803s is about USD 500) and it made a huge difference.
Yes there are many PCB copies on the market of a number of old pre-amps. Are they any good ? they are ok, but you need to spend more money on the Power Supply, components are not cheap if you want something serious. In the end these PCB's are for people who have limited budget to start off with, then over time upgrade and have more fun. I read that they are not bad, but will never will be like the real thing as choice of components and power supply changes the sound dramatically.
I don't know how good your DIY skills are or what type of cartridge you are planning on, but if you like valve phono then you might want to check out what Malcolm is using which is the Ming Da, others have tried the Bottlehead Seduction. EAR 834P is not cheap but Classiquie ounds in UK are selling one for GBP549 which is reasonable.
http://www.classiquesounds.co.uk/ Personally I find phono amplifiers and SUT's are a mine field as you really need to know how to match in get the best sound, and this is not as straight forward as some people think. The tried and tested route is MM tube phono + SUT (Altec Peerless 4722) with a Denon 103 or 103r.
Welcome to ask more questions
