The point here is that this is not a realsitic modification, just another of Dan's manufacturer bashing threads. Remember a few months (about a year ago?) ago when Dan started a huge flame war on headwize by calling the Headroom TA (and everthing else they build) is a total ripoff and that he could build somthing better for $30? I'm sure tyll and danny do...
funny that most here think is a "loss leader", while Dan thinks its a big ripoff.
The "mod" is not an average audiophile tweek. Its a compete rebulding of the amp, using parts that is substantially more expensive than the parts for rest of the amp combined. Would you "tweak" a 486 by bolting in a P4 2GHz? Aside from being a total waste of a part, theres the fact that the parts (2 reistors, two large capacitors, and an opamp buffer) will not fit into the case. Finally, if you are able to solder in several resistors, capacitors, and opamp buffers, you have more than enough skill to build that amp from scratch.
And adding large electrolytics to remove poweron thumps? The most plausible theory for turn-on thumps is a reverse current flow comming from powersupply electrolytics, the larger the capacitance, the larger the thump. Adding large electrolytics may improve bass/transient response, but it won't decrease turn-on thump.
In any audiophile amp, the acutal amp section should always much cheaper than the powersupply. So the cheap opamp based circuit is not really out of line for its price range, which is why it compares favourably with other amps at that price. But whereas other amps like the creek must spend $50 + on a regulated/filtered supply so it can run off AC, the Grado spends $1 for battery clips. That is where the cost-cutting went, if you can accept using batteries, then the RA-1 is not bad at all. But many people here find it an inconvenience. As rick said, adding a powersupply is the only real "modification" that can be done to the amp.