The 17-year-old playmaker is in Italy – along with his father, former Socceroos midfielder Vince Grella and London-based agent Frank Trimboli – to discuss personal terms with the three-time Italian champion.
The deal, which could see Glory reap in excess of the $1.3 million Central Coast Mariners received in 2012 from Guangzhou R&F for Rostyn Griffiths, is close to being finalised.
Under FIFA regulations De Silva – who turns 18 next March – would not be allowed to complete a permanent switch until his next birthday, meaning he would be loaned back to Glory next season.
Glory chief executive Jason Brewer declined to confirm the identity of the club in question but conceded that the eventual exit of Australian youth international would command a record-breaking free.
'It’s our understanding that if an agreement is reached it will set a new record," he said. 'Daniel is contracted with us until July, 2015 – and he will remain with us next season no matter what happens.
'Opportunities like this for a young Australian player don’t come along too often. Of course we would love to keep him but when you look at the bigger picture to get a player of his age going over to one of the top leagues in Europe reflects incredibly favourably on Australian football.
'These types of transfers raise the profile of our game and shows what is possible and helps set the dreams of young kids alight.
'They all want to play in the top leagues of Europe – and we have been able to help make that happen for one player."
De Silva returns to Australia on Saturday and will not be involved in the home clash against Newcastle Jets the following day because he has not trained all week.
Brewer believes that by the end of the season, a final agreement will be in place with Roma – which lies second in Serie A and is bound for the UEFA Champions League next season.
'I am waiting to see what happens with personal terms at the club in question but in terms of a fee we are hopeful that is close to being agreed. Though, of course, the devil is sometimes in the detail."
De Silva, who has made seven appearances for Glory this season, was heavily linked with Serie A clubs Catania and Cagliari earlier in the season without reaching an agreement with either.