The gang - which included an ex-Met police officer imprisoned earlier - smuggled most of the banned substances from Holland and then used a lock-up garage near London as a distribution depot.
Inner London Crown Court heard the operation - headed by a Mr Big too ill to ever stand trial - made millions as orders were delivered across most of southern England and all of Wales.
Kenneth Millett, prosecuting, said neither he nor any of his minions suspected police spent six months watching their every move.
Investigators quickly realised those involved were enjoying an "extravagant lifestyle" despite their obvious lack of jobs.
Day-to-day operations chief and "treasurer" Robert Burnell, for example, drove an Audi TT, had wardrobes crammed with designer clothes and paid for everything in cash.
The investigation, codenamed Operation Carbonel, gradually dismantled the gang's lucrative enterprise with a series of swoops across the country.
During the raids, officers found an amphetamines factory in another lock-up - the gang supplied £650,000 of the drug altogether - and retrieved a library of detailed accounts listing all its deals.
They revealed that apart from the amphetamines, the defendants sold one million Ecstasy tablets worth £5 million, and skunk cannabis - sold mainly in London - with a street value of £1 million.
Police also discovered £80,000 cash and a "large quantity" of Rolex watches in a safety deposit box.
In the dock were Burnell, 37, of Ribway, Buntingford, Hertfordshire (12 years); David Sangster, 40, from Webster Road, Southall, Middlesex (10 years), who organised the drug shipments, and Gary Pettican, 37, the gang's "distributor and facilitator" of Matlock Gardens, Hornchurch, Essex, (three-and-a-half years).
Two other men, Joseph Fisher, the gang's 39-year-old "bookkeeper", of Pavilian Drive, Leigh-on-Sea, and Oliver Jenner, 40, of Shepherd's Croft, Stroud, Gloucester, got 14 and eight years respectively.
All five had variously admitted conspiracies to supply the Class A,B, and C drugs between September 1, 2006, and February 28 the following year.
Passing sentence, Judge Roger Chapple told them: "Unlawful drugs wreck the lives of those who become addicted and wreck the lives of the families and those connected to them. Drugs kill and engender crime.
"When supply networks are brought to justice it is both appropriate and apt that those participants are firmly dealt with.
"These courts will do all in their power to stem or at least reduce those effects.
"The amounts of drugs involved in these conspiracies was absolutely massive."
"Thanks to the vigilance, professionalism and dedication of the police the activities of these conspirators are now over," he added.
After the case, Detective Inspector Grant Johnson said: "This case demonstrates the Met's fight against the criminal networks who operate nationally, importing vast quantities of controlled drugs for distribution across the UK.
"The Projects Team of the Metropolitan Police Specialist Crime Directorate continue in their efforts to dismantle and disrupt these networks and to stem the flow of drugs across the country.
"In this case we have dismantled a highly sophisticated and professional drug syndicate."
He added: "These convictions are the result of months of work between law enforcement agencies in the UK and the sentences represent the substantial damage these drugs would have caused."
Former policeman Andrew Shepherd, 46, from Hornchurch, Essex, who used to be stationed in Romford until he quit on health grounds in 2001, pleaded guilty to conspiracy to supply cocaine at an earlier Kingston Crown Court hearing and was jailed for 36 months.
Two other gang members have also been dealt with. Robert Gregory, 64, who lived in Ferndale, south-west London, admitted plotting to supply cannabis and got 18 months at Inner London Crown Court.
Matthew Ryder, 33, of Ford Close, Ivybridge, Devon, pleaded guilty to a similar charge at Exeter Crown Court and also received 18 months.
