sony scd-1 versus 9000es

I'm not sure I understand your question. A few more words would have helped. The technology in the 9000 is marginally better, but the construction, and cabinet in the SCD 1 are better than the 9000.
I would not trade my SCD 777es for the 9000, you should not trade your SCD 1 for the 9000 modded or not.

I will be more clear.To upgrade my digital front end -I have a few options.I have the atc 150 asl speakers,Levinson 380s and the Scd-1 with a rel storm sub.My sony scd-1 has been modified by Warren Gregoire(vacuum state electronics agent in western US)-it has the stage 2 mod.To improve my stereo I thought of going with multichannel atc speakers,atc subs 6,?emm lab front end viz cdsd/switch 2/dac6e or just keeping the scd-1 and doing a stage 4 mod with vsei and purchasing the Meridian 861 pre. Any feedback?

I was wondering therefore, how the sony 9000es modded with stage 4 vsei stacked up against the modded scd-1?

I would just have the 4.5 mod done to your scd-1. I have a scd-1 with the same vsei upgrade that yours has. I plan on sending mine in for the 4.5 upgrade. The 9000 is pretty flimsy compared to the scd-1. No way would I give up my scd-1 for a 9000. I have spoke to Allan Wright, Warren Gregorie, and Bill Thalmann about this and they all say that the 4.5 upgrade will provide a major improvement in sound. The 4.5 mod is about $450 to $500 as opposed to MAJOR bucks for a dac6.